The Pegan Diet: 21 Practical Principles for Reclaiming Your Health in a Nutritionally Confusing World

Overall score

Scientific accuracy

Reference accuracy

Healthfulness

How hard would it be to apply the book's advice? Very difficult

Book published in 2021

Published by Little, Brown and Company

First Edition, Paperback

Review posted October 5, 2022

Primary reviewer: Samuel Dicken

Peer reviewer: Mario Kratz

Table of contents

1. Introduction
2. Scientific accuracy
3. Reference accuracy
4. Healthfulness
5. Most unusual claim
6. Other
7. Conclusion
8. Updates

Claim 1

Carbohydrates (sugar and starch) cause weight gain.

Supporting quote(s) and page number(s)

Page 5: “The more sugar and starch you eat, the higher your insulin levels. More insulin, more fat storage, more inflammation, more hunger, more immune suppression”.

Page 10/11: “One in two Americans has prediabetes or type 2 diabetes, and 75 percent are overweight. This is the result of the mountains of sugar and flour we consume, which leads to high glucose and insulin, which creates a domino effect. It drives excess calories into fat cells that then produce messengers to increase hunger, slow metabolism, prevent fat burning, and cause inflammation to spike.” 

Page 52: “We all followed the low-fat advice provided by experts and our government for the last 40 years. What happened? We got fat and diabetic – big time.”

Page 55: “What you eat with these fats is what matters. Butter in your cookies may be deadly, while butter on your veggies may be healthful. Key take-home: Do not eat saturated fats in combination with starch and sugar (which unfortunately is how most people consume them); that causes inflammation, weight gain, diabetes, dementia, and heart disease.”

Page 57: “Fat won’t make you fat, unless you eat it with starch and sugar, as so many people do.”

Page 71: “Now we live in a sea of sugar, which causes our biology, especially our hormones, brain chemistry, and immune system, to go haywire, increasing cravings and fat storage (in our belly and around our organs), slowing our metabolism, and fueling our epidemic of obesity, heart disease, diabetes, cancer and dementia.”

Page 71: “Why is 63 percent of the UK (and increasingly the world) overweight? It’s sugar and starch, not fat, that is killing us all.”

Criterion 1.1. How well is the claim supported by current evidence?

2 out of 4

This claim received a score of 2, meaning that it is weakly supported by current evidence. The Pegan Diet states that eating carbohydrates (sugar and starch), but not fat, leads to weight gain and obesity. The book also claims that fat intake can only result in weight gain when consumed with carbohydrates. There are no references provided to support these claims.

Obesity is a condition where there is excessive fat storage that may impair health. Multiple theories exist that attempt to explain what causes obesity. The claim made in The Pegan Diet is based on the carbohydrate insulin model of obesity (CIM). However, the leading theory for explaining obesity is the energy balance model (EBM).Two recently published papers have discussed these models, and whether obesity is driven by an energy surplus from a range of factors (the EBM), or driven specifically by fat storage from the impact of carbohydrate intake on insulin levels (in particular, diets with a high-glycemic load, such as those high in sugar and/or starch) (the CIM).

An updated version of the CIM was published after the release of the book. According to the previous version of the CIM (at the time of publication of The Pegan Diet), the insulin response to a high-glycemic load meal is a critical trigger of overeating and weight gain. Insulin promotes storage of the consumed energy into fat, muscle and liver in the hours following the meal, favoring deposition into fat stores. Over a few hours, levels of fuels in the blood (e.g. glucose and fat) fall due to the persistent action of insulin, and fuels may drop below basal fasting levels. This triggers a ‘starvation’ signal from metabolically active tissues that need energy such as the brain and muscles, increasing hunger and cravings, in particular for high glycemic-load foods. This then promotes increased food intake, an energy surplus and further weight gain. In this version of the CIM, fat storage from the action of insulin after a carbohydrate-rich meal drives us to overeat calories.

In contrast, the energy balance model (EBM) states that body weight is regulated by the brain, whereby different aspects of our food environment influence energy intake, such as cost, taste, accessibility, and energy density. According to the EBM, multiple factors can impact our calorie intake, which in turn drives fat storage.

Evidence at multiple levels (lab studies, epidemiological evidence and controlled human trials) contradicts core aspects of the CIM. From a practical viewpoint, if the CIM were true, then a low-carbohydrate diet would be superior to a low-fat diet for preventing weight gain and promoting weight loss. It would be hard to gain weight on a high-fat diet, but easy to gain weight on a high-glycemic load or high-carbohydrate diet. And, it would be easy to lose weight on a high-fat diet, but hard to lose weight on a high-glycemic load or high-carbohydrate diet.

However, randomized controlled trials indicate that this is not the case. A recent meta-analysis of 32 controlled feeding trials comparing weight loss via either restricting carbohydrates or fats (with calorie and protein intake held constant) showed that dietary macronutrient composition has little impact on body fat loss.

As for sugars, refined carbohydrates and the importance of glycemic index/load for weight regulation, a systematic review and meta-analysis reports that low-glycemic index diets were not superior for weight or fat loss compared to any other control diet. For example, a 12-week randomized controlled trial showed that a low-glycemic load or low-glycemic index diet did not result in superior outcomes for weight loss compared with a calorie-matched, high-glycemic load diet in individuals with obesity. Other randomized controlled trials have replicated these findings, showing no effect of carbohydrate intake or glycemic index on weight or fat loss with energy-matched, calorie restricted diets varying in carbohydrate content and glycemic index. The results from ad libitum feeding trials (where energy intake is not controlled) also do not support the idea that reducing carbohydrate intake will lower energy intake. For example, a recent metabolic ward crossover trial demonstrated that an ad libitum, high-carbohydrate, high-glycemic load, low-fat diet resulted in a lower daily energy intake than an ad libitum, low-carbohydrate, low-glycemic load, high-fat diet. These findings are not to say that consuming too much sugar or other refined carbohydrates cannot lead to weight gain. Excess intakes of free or added sugars, such as those found in sugar-sweetened beverages, are associated with an increased risk of weight gain, from excess energy intake. As such, there are recommendations from health organizations to reduce their consumption. However, The Pegan Diet suggests that forms of sugar drive weight gain, not from excess energy intake, but from consuming the sugar itself and the subsequent insulin response driving fat storage and increased hunger. However, the evidence to date showing no meaningful difference in weight loss between low-fat and low-carbohydrate diets over 12 months strongly refutes this claim.

In summary, the evidence to date, at best, weakly supports the idea that carbohydrates (sugar and starch) cause overeating and weight gain as a result of elevated insulin after a meal. Randomized trials demonstrate that high-carbohydrate diets can spontaneously lower energy intake and body weight, and that high-carbohydrate diets are as effective as low-carbohydrate diets for weight loss. The claim was given a score of 2, to reflect that multiple lines of evidence and experimental trials contradict core aspects of the CIM as a model of obesity, and provide stronger support for the EBM, indicating that multiple factors can influence energy intake, not just sugar and starch consumption.

Criterion 1.2. Are the references cited in the book to support the claim convincing?

1 out of 4

The book does not cite references to support this claim. Therefore, The Pegan Diet scored 1 for this criterion, meaning its references neither support nor refute the claim.

Criterion 1.3. How well does the strength of the claim line up with the strength of the evidence?

1 out of 4

The claim received a score of 1, meaning that the evidence is much more uncertain than the claim suggests. The evidence from both human observational studies and experimental studies indicate that carbohydrate (sugar or starch) consumption alone does not drive weight gain. Diets low in carbohydrates do promote weight loss, with current evidence suggesting that this weight loss is not meaningfully different from weight loss diets high in carbohydrates over the long run.

Overall (average) score for claim 1

1.3 out of 4

Claim 2

Carbohydrates (sugar and starch) are the primary cause of insulin resistance and type 2 diabetes.

Supporting quote(s) and page number(s)

Page 2: “[I]nsulin resistance (from too much starch and sugar)”

Page 5: “Sugar and starch are hidden in all processed food. They create a chain reaction, causing blood sugar to spike, which causes insulin to spike, leading to insulin resistance. 

Page 21: “Un-fortunately, our modern diet is rich in damaging refined carbs – pizza, fries, bread, pasta. These are the types of nutrient-stripped foods that drive high blood sugar, inflammation, and insulin; raise your triglycerides, lower your good cholesterol; and fuel diabetes, cancer, dementia and heart disease.”

Page 32/33: “Whole wheat bread is worse for you than plain old sugar. Flours of any kind in the form of bread, pasta, muffins and pastries are the source of most metabolic disorders.”

Page 86: “Often, high insulin and blood sugar are the result of too many starches and sugars, too much stress, and not enough movement.”

Page 115: “How does insulin resistance happen? Simple: When you overeat starch (flour, pasta, bread, rice, and refined grains) and sugars in any form, your pancreas pumps out loads of insulin. Your cells become resistant to its effects, meaning that more and more insulin is required to keep your blood sugar normal. Until it can’t, and then you get type 2 diabetes and a host of other problems, like increased belly fat, muscle loss, inflammation, hormonal imbalances and brain damage.”

Page 116: “For some of you already down the road of poor metabolic health, it may be critical to fix your metabolism by eliminating all starch and sugar for a few months or even a year. Over time, removing these foods will make you insulin sensitive and able to ease back into eating starchy veggies, fruits, beans, and whole grains.” 

Page 118: “Focus on fixing insulin resistance… Remove all sugars and refined starches from your diet, including bread, pasta, rice, and potatoes.”

Criterion 1.1. How well is the claim supported by current evidence?

2 out of 4

This claim received a score of 2, indicating that it is weakly supported by current evidence. The Pegan Diet claims that consuming carbohydrates (sugar and starch) is the primary cause of insulin resistance and type 2 diabetes, and as such, these can be fixed by eliminating sugar and starch.

The primary cause of insulin resistance is considered to be a chronic energy surplus leading to excess fat storage, rather than from consuming a specific nutrient per se. Where the surplus gets stored is important. Typically, fat is stored under the skin (subcutaneous fat). If the energy surplus exceeds the capability to store it in subcutaneous fat, it can end up ‘spilling over’ and being stored around our organs (visceral fat), or in places where it is not usually stored in large amounts (ectopic fat), such as the liver, heart or muscle. When fat gets stored in these locations, it can impair the ability of these tissues to respond to circulating insulin, and they start becoming insulin resistant. The greater the size and duration of the energy surplus, the greater likelihood of storage in ectopic or visceral fat stores. Someone does not have to be living with obesity for energy ‘spillover’ into ectopic or visceral fat stores. The ability to handle the energy surplus is highly variable between people and dependent on many factors (such as genetics, age, smoking or physical activity). Some individuals may experience no metabolic problems despite large gains in fat mass (being stored in subcutaneous fat), whereas others experience small increases in fat mass in ectopic stores and develop insulin resistance (the personal fat threshold hypothesis).

Excess energy deposition in visceral and ectopic fat stores are the primary determinants of insulin resistance. However, there is some evidence to suggest that elevated insulin concentrations per se can induce insulin resistance. Because a diet rich in sugar and starch triggers repeated spikes in blood sugar and insulin, it stands to reason that theoretically such a diet may be the main factor leading to insulin resistance. However, the situation is more complex than the book suggests. If carbohydrate intake is reduced in favor of saturated fatty acids, for example, the result may be even greater insulin resistance. This is consistent with meta-analyses of controlled feeding trials showing that replacing saturated fats or carbohydrates with polyunsaturated fats or monounsaturated fats tends to improve insulin sensitivity, whereas replacing carbohydrates with saturated fats has a minimal effect on insulin resistance.

The Pegan Diet also claims that sugar and starch are the primary cause of type 2 diabetes. Type 2 diabetes is a combination of insulin resistance and a failure of pancreatic beta cells (the cells that produce insulin) to produce sufficient insulin, where blood sugar levels are high, even when fasted. From a dietary perspective, type 2 diabetes is likely also predominantly an issue of chronic energetic excess and having too much fat stored in ectopic depots, such as in the liver and pancreas (the twin cycle hypothesis), rather than from sugar and starch intake per se. Alongside liver fat accumulation during an energy surplus, fat accumulation in the pancreas impairs the ability of beta cells to produce sufficient amounts of insulin after a meal. Eventually, the beta cells become dysfunctional and cannot compensate for the need for greater insulin secretion that results from insulin resistance, leading to a rapid rise in blood sugar and type 2 diabetes.

Given their proposed role in being the main cause of insulin resistance and diabetes, The Pegan Diet claims that metabolic health can therefore be improved by reducing or eliminating all sugar and starch intake: “For some of you already down the road of poor metabolic health, it may be critical to fix your metabolism by eliminating all starch and sugar for a few months or even a year. Over time, removing these foods will make you insulin sensitive and able to ease back into eating starchy veggies, fruits, beans, and whole grains.” (page 116), “Focus on fixing insulin resistance… Remove all sugars and refined starches from your diet, including bread, pasta, rice, and potatoes.” (page 118).

However, this is weakly supported by scientific evidence. A recent systematic review of low-energy and low-carbohydrate diets for treating type 2 diabetes showed that improvements in blood sugar levels were strongly associated with the average amount of weight loss achieved at the end of the study, regardless of the dietary method used. A 2018 meta-analysis of diet interventions to improve insulin resistance or fasting blood sugar levels in people with type 2 diabetes showed that a low-carbohydrate diet was no more effective than a Mediterranean diet in improving blood sugar levels. Weight loss is the primary driver for improving insulin sensitivity, which can be successfully achieved across a range of carbohydrate intakes. And similarly for diabetes remission and improvement in blood sugar levels, via reductions in liver and pancreas fat (reversing the twin cycle) from weight loss, with restoration of beta cell function and improved insulin sensitivity.

The Pegan Diet highlights the potential metabolic impact from consuming sugar and refined starches, which tend to have a higher glycemic index, and the need for their elimination. When instead considering the impact of high- vs low-glycemic index diets on insulin resistance and blood sugar control in longer term randomized trials, these also tend to be equivocal. In a recent randomized controlled trial comparing a weight maintaining, isocaloric, high- or low-glycemic index Mediterranean diet, the glycemic index of the Mediterranean diet had no influence on changes in fasting blood sugar or measures of insulin resistance over 12 weeks. The OmniCarb trial assessed the impact of both the glycemic index and quantity of carbohydrate in the context of a healthy diet pattern on insulin sensitivity. After 5 weeks, there were no differences in insulin sensitivity between a low-glycemic index, low-carbohydrate diet, and a high-glycemic index, high-carbohydrate diet. There was no benefit on insulin sensitivity to lowering the glycemic index of a high-carbohydrate diet, or lowering the glycemic index of a low-carbohydrate diet.

The claim that temporarily eliminating sugar and starch improves metabolic health so that at a later date the body can handle starchy foods again is also not supported. Lowering carbohydrate intake does not necessarily confer a benefit to metabolic health, which would be expected if consuming carbohydrates was the primary cause of poor metabolic health. Glucose tolerance (the ability to keep blood sugar levels within the normal range in response to eating carbohydrates) tends to be better on a diet containing carbohydrates, including those containing starch or sugar.

Two feeding studies have compared a lower-carbohydrate, higher-fat diet (43% carbohydrate, 39% fat) with a higher-carbohydrate, lower-fat diet (55% carbohydrate, 27% fat) on insulin sensitivity and blood sugar control. In individuals with normal blood sugar control, insulin sensitivity was significantly lower after an 8-week lower-carbohydrate diet than after an 8-week higher-carbohydrate diet. In people with impaired blood sugar control, fasting blood sugar was higher and beta cell function was lower after an 8-week lower-carbohydrate diet than after an 8-week higher-carbohydrate diet. In adults living with overweight, an 8-week lower-carbohydrate diet did not benefit beta cell responsiveness and had no impact on insulin sensitivity compared with an 8-week higher carbohydrate diet. Of course, while consuming a low amount of carbohydrates, a lower glucose tolerance is not necessarily an issue, and with the reintroduction of carbohydrates, glucose tolerance improves. But, this does not support the assertion that eliminating sugar and starch will benefit metabolic health to facilitate the reintroduction of carbohydrates.

Even so, there is still some uncertainty and an ongoing debate surrounding the direct role of added sugar intake on metabolic health. Wwhile there is evidence that free or added sugars can directly decrease insulin sensitivity and impact on mechanisms of insulin resistance and diabetes progression, these studies tend to use liquid sugars containing fructose, which may not apply to sugars consumed as solids. Well-designed trials that examine the impact of different forms of sugar intake on the development of insulin resistance and diabetes independent of weight gain are needed to provide greater certainty.

In summary, sugar or starch consumption per se does not appear to be the primary cause of insulin resistance or type 2 diabetes. Instead, from a dietary perspective, insulin resistance and the development of type 2 diabetes is primarily the result of energy overconsumption and an increase in ectopic fat storage. Reducing sugar and starch intake may support energy restriction, weight loss and improvements in metabolic health, but there does not appear to be an inherent benefit to reducing sugar and starch intake or reducing the glycemic index of the diet. The claim was given a score of 2 to reflect the body of evidence showing weak evidential support, but some uncertainty regarding the magnitude of a direct effect of free or added sugars on metabolic health due to limitations in study designs of existing studies.

Criterion 1.2. Are the references cited in the book to support the claim convincing?

1 out of 4

There are no references cited in The Pegan Diet that relate to the causes of insulin resistance or type 2 diabetes, therefore The Pegan Diet scored 1, meaning its references neither support nor refute the claim.

Criterion 1.3. How well does the strength of the claim line up with the strength of the evidence?

2 out of 4

The claim received a score of 2, indicating that the claim is moderately overstated, and the effect more uncertain than is claimed. Energy restriction and weight loss appear to be the key factors for improving insulin sensitivity and blood sugar levels, rather than simply restriction or elimination of sugar, starch or carbohydrates in general.

Overall (average) score for claim 2

1.7 out of 4

Claim 3

Wild, organic, pasture-raised or grass-fed animal-based food promotes good health, whereas conventional, industrial, factory-farmed or grain-fed animal-based food promotes disease.

Supporting quote(s) and page number(s)

Page xv/xvi: “If you eat industrial food, even vegetables, your diet will be depleted. Organic vegetables are more nutrient dense. Factory-farmed cows fed a simplified diet of corn, cow poop, candy, and ground-up animal parts produce meat that leads to inflammation and disease. Wild elk or regeneratively (organically) raised cows that forage on dozens of medical plants produce meat that has the opposite effect.”

Page 35: “Is bison or wild elk the same as a feedlot steak for your health, the well-being of the animals, or the health of the environment? Absolutely not.”

Page 42: “As outlined in a remarkable paper titled “Health Promoting Compounds Are Higher in Grass-Fed Meat and Milk”, published in Frontiers in Nutrition, scientists from Duke University found healing phytochemicals in grass-fed meat, such as terpenoids, phenols, carotenoids, and antioxidants with anti-inflammatory, anti-carcinogenic, and cardioprotective effects.” (Paper not actually referenced in the book and incorrect article title).

Page 43: “There are many types of saturated fat, all with different properties. Fat in regeneratively raised grassfed meat is different from fat in corn-fed meat.”

Page 46: “Conventional chickens are pumped full of corn and antibiotics, making them fatter than ever and their meat less nutritious than ever.”

Page 49: “Luckily, there’s a way to choose fish that is rich in nutrients and low in toxins – specifically, wild-caught and sustainably harvested farm-raised fish.”

Page 98: “Feedlot meat is bad. Regenerative, grass-fed, or wild meat in the context of a plant- and spice-rich whole foods diet promotes health and is better for the environment and climate than a plant foods-only diet.”

Criterion 1.1. How well is the claim supported by current evidence?

2 out of 4

This claim received a score of 2, meaning that it is weakly supported by current evidence. The Pegan Diet claims that organic (or wild, pasture-raised, grass-fed) animal-based food is healthy, and conventional (or industrial, factory-raised, grain-fed) animal-based food is unhealthy. This is based on the claim that organic and conventional animal-based foods differ in terms of their nutrient and phytonutrient composition, which impacts on health.

There is good evidence that food production methods can alter the nutrient content of animal-based foods, and in particular, that organic food production tends to result in a slightly more favorable nutrient profile. But, these differences tend to be minor. For foods such as beef or milk, the differences between organic (typically grass-fed) and conventional (typically grain-fed) food tends to reflect the differences in the feed of the animals. For example, grass-fed beef contains more omega-3 fatty acids than grain-fed beef, but grain-fed beef has a higher monounsaturated fatty acid content. Grass-fed meat and milk may also contain greater levels of certain phytonutrients. However, besides the method of production and type of nutrition of the animal, other factors can influence the nutritional composition of animal-based foods, including seasonality, species, or geography.

Despite differences in composition, there is little evidence as to whether consuming organic versus conventional animal-based foods results in different health outcomes. No randomized controlled trials exist that have compared the long-term health effects of eating organic vs. conventional animal-based foods, mainly because such a trial is cost-prohibitive in the absence of at least suggestive data that disease risks could be differentially affected.

There are a handful of trials that compare a single meal containing organic or conventional foods, or that compare diets rich in organic vs. conventional foods over the course of a few days or weeks. Short-term trials can look at biomarkers of health (e.g. changes in blood vessel function, or biomarkers of oxidative stress or metabolic health), but not hard disease outcomes. The evidence to date does not indicate a meaningful difference for health. For example, giving healthy men pasture-raised beef burgers or grain-fed beef burgers which differed in monounsaturated:saturated fat content, five times a week for 5 weeks, had no impact on biomarkers of inflammation, but HDL cholesterol increased after eating the grain-fed beef burgers compared with the grass-fed burgers. In another trial, 8 weeks of consuming ground beef and dairy from pasture-fed cattle rich in conjugated linoleic acid had no impact on body composition, insulin sensitivity or blood lipids, compared with consuming ground beef and dairy from grain-fed cattle, with both diets matched in terms of macronutrient composition.

We could also use observational data to see if different food production methods are associated with better or worse health outcomes. However, the most common methods of assessing diets in large observational studies, food frequency questionnaires (e.g. ‘how often did you eat a portion of this food in the past week?’) or dietary recalls (e.g. ‘what did you have for lunch?’), typically do not capture this level of information (whether organic or conventional). Therefore, most observational evidence to date provides information on the association between food groups and health outcomes regardless of the production method, and is unable to support (or refute) the claim being made here.

There are a handful of observational studies that compare organic and conventional foods. However, most of these are cross-sectional, which makes it harder to determine the direction of association, they do not assess major health outcomes such as cardiovascular disease, cancer or mortality, and they tend to consider both animal- and plant-based organic foods.

In the French NutriNet-Sante cohort, a higher frequency of organic food consumption was associated with a lower risk of non-Hodgkin lymphoma and postmenopausal breast cancer, but not with any other type of cancer. In the UK Million Women Study, organic food consumption was not associated with a reduced risk of cancer.

It is important to consider that the associations between organic food and health outcomes from observational studies may also be influenced by confounding factors. For example, organic food consumers are more likely to have other health promoting behaviors and characteristics associated with improved health (such as higher education and socioeconomic status, a healthier diet and greater physical activity).

A recent study modeled the expected changes in intake of different types of fat from consuming beef from different production methods. They showed a theoretical benefit on meeting recommended intakes of omega-3 when switching to pasture-raised beef from conventional beef. This was based on consuming the government recommended upper limits of red meat (70g red meat per day, assuming all red meat consumed was beef). However, when modeling was based on actual current average UK intakes of fat from beef (3g fat from beef per day), these differences in omega-3 intake were negligible. This study also highlights a further complication; there are different terms used within animal feeding systems (e.g. organic, grass-fed, wild, pasture-fed), which all involve slightly different production methods, such as some using grain feeding only, or a mix of grain and grass feeding of animals. These can influence the nutrient content of the final food product, which adds to the complexity of comparing non-conventional with conventional animal-based foods.

The claim that conventional animal-based foods are harmful to health is not supported by the evidence. Unprocessed meat, chicken and dairy are nutrient dense food sources that contribute to meeting population nutrient intakes in the US and UK. Longitudinal observational studies show that poultry, fish and dairy are generally associated with a reduced risk, or neutral association with all-cause mortality (fish, poultry, dairy), cardiovascular disease (fish, poultry, dairy) or cancer (fish and poultry, dairy). In contrast, unprocessed red meat tends to be associated with detrimental health outcomes (cardiovascular disease, diabetes, cancer), with a smaller associated risk than for processed red meat.

In conclusion, while there is good evidence that the method by which animals are raised (e.g. organic vs conventional production methods) can alter their nutritional profile, these differences appear to be minor, with a lack of robust evidence showing whether these differences influence health or disease risk in humans. The claim that these production methods result in contrasting health outcomes (increased risk of disease or a reduced risk of disease depending on the food production method) is weakly supported. As summarized in a recent review: “It is increasingly accepted that there can be nutritionally relevant composition differences between organic and conventional foods and there is some evidence for potential benefits of organic food consumption from human cohort studies. However, considerable uncertainty/controversy remains on whether or to what extent these composition differences affect human health.” 

Criterion 1.2. Are the references cited in the book to support the claim convincing?

2 out of 4

The book’s references received a score of 2 (the main supporting review was not actually cited for some reason, but quoted and described in detail on page 42), indicating that they are weakly convincing and only partially support this claim.

The main evidence provided in support of the claim was a review of the nutrient content of grass-fed meat and milk. The review provides good and comprehensive evidence that there are some nutritional differences between grass-fed meat and dairy and conventional grain-fed meat and dairy. But, the review does not provide any evidence for differences in health outcomes, and in fact provides much greater uncertainty regarding the health benefit of organic foods over conventional foods than The Pegan Diet claims: “How increasing the phytonutrient density of animal foods will modify potential relationships between consumption and metabolic health of consumers needs to be further addressed in clinical studies.”. 

A minor section in reference 19 also supports the idea that organic milk may have higher omega-3 and beta carotene than conventional milk, as a result of grass-feeding.

Criterion 1.3. How well does the strength of the claim line up with the strength of the evidence?

1 out of 4

The claim received a score of 1, indicating that the claim substantially overstates what current evidence suggests. This is due to the fact that most evidence to date compares the composition of organic (or grass-fed) animal-based foods and conventional (grain-fed) animal-based foods, but provides little human evidence showing differences in health outcomes as a result. While there might be minor compositional differences between such foods, the claim that this difference results in conventional foods being unhealthy and increasing risk of disease, and organic foods being healthy is substantially overstated and not supported by the evidence.

Overall (average) score for claim 3

1.7 out of 4

Overall (average) score for scientific accuracy

1.6 out of 4

Reference 1

Reference

Chapter/Principle 2: Eat the Rainbow, reference 11.  NHS. Five a day of fruit and veg is good but 10 is better. 

Associated quote(s) and page number(s)

Page 17: “The US Dietary Guidelines recommend a minimum of 240 grams of veggies per day (or 5 to 9 servings of fruits and vegetables, where a serving is 40 grams). The optimal amount should be 480 to 640 grams or 12 to 16 servings.[11]”

Criterion 2.1. Does the reference support the claim?

1 out of 4

Reference 11 is a link to a National Health Service (NHS) webpage. This page has now been retired, but an archived version is available on Wayback Machine. The page is an analysis of a report by The Guardian of a scientific paper. The archived page does not mention the US Dietary Guidelines, or 240 grams of vegetables. It is also notable that the National Health Service (NHS) is a UK government organization, not associated with the US Dietary Guidelines. The link itself is not evidence for the claim, nor is the Guardian report that is being referred to. This citation is not relevant at all to the claim it’s associated with.

Of note, a fruit or vegetable portion in the UK is 80g fresh, not 40g, so 10 portions would be 800g, not 480-640g.

Reference 2

Reference

Chapter/Principle 2: Eat the Rainbow, reference 9.  Gupta and Prakash et al. J Complement Integr Med. 11(3):151-69. 2014. PMID: 25051278

Associated quote(s) and page number(s)

Page 16: “If food is medicine, think of plants as the most powerful medicine in your farmacy with the vast array of colors representing more than 25,000 beneficial chemicals. You may have heard of these phytochemicals or phytonutrients before. They include polyphenols, resveratrol, flavonoids, isoflavonoids, terpenoids, and carotenoids, to name a few, and they play a significant role in creating optimal health and disease prevention. These compounds benefit our biology in hundreds of ways. They boost immunity, reduce inflammation, and have anti-cancer and anti-aging effects.[9]”

Criterion 2.1. Does the reference support the claim?

4 out of 4

This reference received a score of 4, indicating that it offers strong support for the claim. The reference is a review discussing the role of phytonutrients as therapeutic agents in human health.

The review discusses each of the phytonutrients in turn, discussing their role in health and disease prevention. The review makes many similar claims as made in The Pegan Diet. Some of the statements about the health properties of certain phytonutrients in the review are not referenced. Claims such as ‘they play a significant role in creating optimal health and disease prevention’ are likely to be overstated, both in The Pegan Diet and in the cited reference. The references in the paper are mainly from lab studies, rather than examining the impacts of these compounds in humans.

Reference 3

Reference

Chapter/Principle 15: Eat for Gut Health, reference 28.  Kang et al. Scientific Reports. 9(1):5821. 2019. PMID: 30967657

Associated quote(s) and page number(s)

Page 104: “A fecal transplant, for instance, reduced autistic symptoms by 50 percent in one study, an improvement that lasted long term. [28]”

Criterion 2.1. Does the reference support the claim?

3 out of 4

This reference received a score of 3, indicating that it offers moderate support for the claim. It is a 24-month follow-up of an intervention which performed a fecal transplant in children with Autism Spectrum Disorder (ASD).

The severity of ASD was 47% lower at 24 months than at baseline following the intervention, as rated by a professional. Symptoms were reported by the parents, which dropped from 89% having severe symptoms at baseline, down to 47% having severe symptoms at 24 months. It is not clear how the book arrived at the 50% reduction figure.

It is also important to note that the study had a number of important limitations, none of which were discussed or disclosed in The Pegan Diet. For one, the researchers, children and parents were fully aware of the procedure being performed (they were not blinded), and as participants were asked about their autistic symptoms by their parents, this may have created a bias from an expectation of improvement. The authors also conclude that the results should be treated as preliminary; there was no control group (for example, participants could have instead received a ‘sham’ transplant with no fecal material transferred as a placebo group), and participants were not randomized to receive the intervention.

The authors note that two thirds of the children had also made changes to their medication, nutritional supplements and diet in the time since the intervention. These changes may have influenced the improvement in symptoms. It is worth noting that these children also had chronic gastrointestinal problems, and the intervention also included antibiotics, a bowel cleanse and the use of a stomach-acid suppressant, besides just the fecal transplant alone. This may have influenced changes in fecal microbiota and ASD symptoms, meaning the changes cannot be attributed to the fecal transplant alone.

Reference 4

Reference

Chapter/Principle 1: Use Food as Your Farmacy, reference 4.  Roberts et al. J Appl Physiol (1985) 98(1):203-10. 2005. PMID: 1533612

Associated quote(s) and page number(s)

Page 9: “Unfortunately, the Standard American Diet is riddled with inflammatory foods like bad fats, bad meat, sugar and starches. Studies show that a single fast-food meal meal harms blood vessels.[4]”

Criterion 2.1. Does the reference support the claim?

2 out of 4

This reference received a score of 2, indicating that it offers weak support for the claim. The evidence cited is an experimental study investigating the long-term impact of two diets on blood vessel function in rats. The rats were given either a high-fat, high-sugar (sucrose) diet, or a standard chow diet (a low-fat, complex carbohydrate diet) from 2 months of age, for 7 months. In some tests, the functioning of the inner lining of the blood vessel (called the endothelium, which is important for healthy blood vessel function) was impaired in the rats fed the high-fat, high-sugar diet, compared with the endothelium of rats on the standard chow diet. There were also adverse changes in oxidative stress on the high-fat, high-sugar diet, that would promote inflammation. However, the impairment was not following a single fast-food meal, but from a long-term diet intervention. There are also a lot of differences between humans and rodents, such that results from a rat experiment cannot be applied to a fast-food meal consumed by a human. The high-fat, high-sucrose diet did not contain meat or starches as mentioned in the quote, or an actual fast-food meal.

Reference 5

Reference

Chapter/Principle 2: Eat the Rainbow, reference 12. Minich. J Nutr Metab. 2019:2125070. 2019. PMID: 33414957

Associated quote(s) and page number(s)

This reference is not associated with a quote, but instead presented at the top of a table of colors of fruit and vegetables and the benefits of consuming foods in each color. The claim is taken as the color of the fruit or vegetable and the associated benefit.

Page 18: “Colors of fruit and vegetables and their properties[12]”

Red: “Anti-inflammatory, general antioxidant activity, immune modulation”

Orange: “Antioxidants for fat soluble tissues, endocrine modulation, fertility support”

Yellow: “Gastric motility and regulation, glycemic impact, supporting gut microbiome”.

Green: ”Antioxidant, blood vessel support, supports healthy circulation and methylation”.

Blue: “Antioxidant, cognitive support, healthy mood balance, role in neuronal health”

Criterion 2.1. Does the reference support the claim?

3 out of 4

This reference received a score of 3, indicating that it is consistent with the claim and is intrinsically moderately convincing. It is a review of the health benefits of fruit and vegetables based on their color. The claim is that the specific color of a food relates to the specific health-promoting properties of the fruit and vegetable. The review outlines the health benefits of each of the five colors above (but blue as blue-purple), and the claims made in the book match those provided in table 2 of the review.

The review subsequently goes through each food color with examples of such foods that are also listed as examples in The Pegan Diet, outlining the health-promoting properties based on lab, animal and clinical studies. The reference supports the claim being made, however the reference itself is of a lower quality. Some of the claims made are rather vague, such as “immune modulation” or “glycemic impact”, which aren’t necessarily health benefits, and may be supported only by evidence from a lab study.

In addition, some of the sections of the review are rather thin given the range of benefits claimed. The orange foods section relies on animal studies and observational evidence to support the fertility-related claim. In addition, claims such as “gastric motility and regulation” are unlikely to be specific to yellow foods, given the high-fiber content in fruits and vegetables of any color and its benefit on gut health. The review and The Pegan Diet highlights methylation as a benefit of green foods, yet methylation is not mentioned or referenced in the text of the review.

Reference 6

Reference

Chapter/Principle 1: Use Food as Your Farmacy, reference 6.  van Bussel et al. J Nutr 145(3):532-40. 2015. PMID: 25733469

Associated quote(s) and page number(s)

Page 10: “Omega-3 fats from wild fish also help improve blood vessel health, and they prevent clotting. [7]”

Criterion 2.1. Does the reference support the claim?

0 out of 4

This reference received a score of 0, indicating that it contradicts the claim made. The evidence is an observational study in older adults with a high risk of cardiovascular disease (e.g. they had a high BMI or family history of diabetes). The researchers examined the association between the consumption of six food groups (fish, vegetables, fruit, alcohol-containing beverages, dairy products and meat) and biomarkers of endothelial dysfunction (a measure of blood vessel health) and low-grade inflammation (which can influence the risk of blood clotting) after 7 years of follow-up. Multiple biomarkers were measured and summed to produce an endothelial dysfunction score, and a low-grade inflammation score.

Total fish intake (100g/week) was associated with a significantly lower endothelial dysfunction score (better blood vessel function), but not with a lower low-grade inflammation score. Total fish intake was then subdivided into fatty fish, lean fish and shellfish. When looking at fatty fish alone, these were not significantly associated with a lower endothelial dysfunction or low-grade inflammation score. However, the association for lean fish intake and a lower endothelial dysfunction score was significant. The study provided evidence that lean fish (i.e. fish that would be lower in omega-3) was associated with improved blood vessel health, but not fatty fish (i.e. fish that would be higher in omega-3). Furthermore, there is no evidence to support the claim that this is specific to wild fish and dependent on omega-3 content; whether the fish was wild or not was not assessed in the study, and neither was omega-3 fatty acid intake.

This was a smaller study within the Cohort on Diabetes and Atherosclerosis Maastricht Study, specifically in participants with an increased risk of cardiovascular disease. The biomarkers used to produce overall biomarker scores for endothelial dysfunction and low-grade inflammation are considered to be relevant and important, such as C-reactive protein and interleukin-6.

The claim is making causal conclusions about omega-3 fats from oily fish, but the evidence cited is observational and cannot make such strong conclusions. This was not an intervention giving people wild fish rich in omega-3s and examining the impact on blood vessel health and clotting. The evidence does not support that omega-3s from wild fish are associated with improved blood vessel health.

Reference 7

Reference

Chapter/Principle 1: Use Food as Your Farmacy, reference 3.  Joe et al. Crit Rev Food Sci Nutr. 44(2):97-111. 2004. PMID: 15116757

Associated quote(s) and page number(s)

Page 9: “Curcumin, found in the Indian spice turmeric, is a superfood that reduces inflammation and oxidative stress and aids detoxification.[3]”

Criterion 2.1. Does the reference support the claim?

4 out of 4

This reference received a score of 4, indicating that it offers strong support for the claim. The evidence is of a review of curcuminoids (which includes curcumin) and their various health promoting properties. The review examines studies on curcumin and its anti-inflammatory and antioxidant properties, as well as examining its effect on detoxifying mechanisms. The evidence is from lab studies as it focuses on the cellular and molecular mechanisms, typically using large doses of curcumin.

Reference 8

Reference

Chapter/Principle 5: Eat Your Meat as Medicine, reference 18.  Li et al. Am J Clin Nutr 91(5):1180-4. 2010. PMID: 20335545.

Associated quote(s) and page number(s)

Page 42: “I also recommend cooking your meat with spices… The slow cooking of meat with dozens of antioxidant and anti-inflammatory spices is protective. Studies show dramatic reductions in oxidative stress markers when meat is consumed with herbs, spices and polyphenols such as red wine, olive oil, and balsamic vinegar. [18]”

Criterion 2.1. Does the reference support the claim?

2 out of 4

This reference received a score of 2, indicating that it is weakly convincing. The evidence is of a randomized controlled trial comparing changes in a single marker of oxidative stress (malondialdehyde) after eating a hamburger with spices, or a hamburger without spices. Red wine, olive oil and balsamic vinegar were not assessed in this study.

Researchers gave participants two burgers in a random order: one with 11.25g of spice (cloves, cinnamon, oregano, rosemary, ginger, black pepper, paprika and garlic powder) added to a ground beef hamburger during cooking, and another without any spice. They then compared changes in malondialdehyde levels in the blood and urine up to 6 hours after consuming the spiced hamburger, or the non-spiced hamburger.

Blood and urine levels of malondialdehyde were lower after eating the spiced burger compared with the burger without spice. The spiced burger had significantly less malondialdehyde content than the non-spiced control burger to begin with (71% less), so it is unsurprising that plasma and urine levels of malondialdehyde were also significantly lower after consuming the spiced burger. Malondialdehyde can be found in certain high-fat foods, and is also produced within the body. It is a measure of oxidative damage to lipids, and occurs following their breakdown. It is not clear from the study if the changes in malondialdehyde are just a result of consuming more malondialdehyde from the non-spiced burger, or whether there were changes in malondialdehyde produced in the body, the latter being more important for health outcomes, as noted in a letter to the editor in response to the study. No other markers of oxidative stress were assessed, yet The Pegan Diet claims multiple oxidative stress markers are reduced.

Some of the food examples given in the claim were not actually examined in the study. The book widens the findings to red wine, olive oil and balsamic vinegar, none of which were tested. And, 11.25g is also a huge amount of spice to add to a single burger, far more than would be typically added.

Reference 9

Reference

Chapter/Principle 17: Eat to Boost Mood, reference 34.  Schoenthaler et al. J Nutr Environ Med. 7(4):343-52. 1997.

Associated quote(s) and page number(s)

Page 122:“Other studies show that kids with violent behavior transform when swapping out processed foods for whole foods. One study of violent juveniles found that simply giving children a vitamin and mineral supplement reduced violent acts by 91 percent compared to a control group. [34] Why were they violent? Their brains were starved of nutrients that regulate mood and behavior, including iron, magnesium, B12, and folate.”

Criterion 2.1. Does the reference support the claim?

3 out of 4

This reference received a score of 3, indicating that it offers moderate support for the claim. This was a randomized, double-blind trial (both the participants and the researchers did not know who received which treatment), in which confined delinquents aged between 13 and 17 were given a vitamin and mineral supplement (three pills daily), or placebo pills for up to 13 weeks. They then compared violent and non-violent antisocial behaviors between the two groups.

The study found reductions in the number of antisocial acts in the participants given the vitamin and mineral supplement, compared with the placebo group. It is not clear where the claim for a 91% reduction in violent acts is from. Violent rule infractions (as a mean weekly rate of violent acts to account for the different lengths of time participants spent in the experiment) fell by 80% in the active group, and by 56% in the placebo group, from baseline to 3 months, resulting in a 24% net difference. Violent acts were not reduced by 91 percent (as claimed in The Pegan Diet) in the group receiving the vitamin-mineral supplement compared with the placebo group.

Reductions in violence were greater in those with improvements in blood vitamin concentrations. In those without a reduction in violent acts, blood vitamin concentrations were unchanged from the start of the study. The benefit of the vitamin and mineral supplement in reducing violent acts is blurred due to the dietary changes that occurred during the trial, which also impacted on blood vitamin and mineral concentrations. At the start of the study, a blinded dietician gave participants with signs of poor nutrition dietary advice to correct their nutritional deficiencies. Many participants in both groups changed their diet, but these changes are not reported for the sample (e.g. nutrient or food group intakes). Regardless of group allocation, the authors found that improvements in blood vitamin concentrations were related to reductions in violence.

However, the analyses on changes in blood vitamin levels and violent acts compare a small sample of participants in each group, which require caution in drawing strong conclusions. The paper provided no detail on the measurement methods of vitamin and mineral concentrations from the blood samples. Nutrient deficiency was also based on an independent sample of incarcerated juveniles without any violent acts for 13 weeks. It is not reported how large this reference sample was. Changes in mineral concentrations were not reported in many of the tables, yet were clearly measured from the text in the results section. The vitamins and minerals cited (iron, magnesium, B12 and folate) are just four of those in the paper that were normalized during the trial period and were related to reductions in violence.

Reference 10

Reference

Chapter/Principle 17: Eat to Boost Mood, reference 33.  Jacka et al. BMC Med. 15:23. 2017. PMID: 28137247.

Associated quote(s) and page number(s)

Page 121/122: “Studies show that simply swapping out processed, sugary, starchy foods for whole foods (fruits, veggies, olive oil, nuts and seeds, legumes, and some meat – think Pegan) is effective in treating depression, in fact, 400 percent more effective than a typical Western diet. [33]”

Criterion 2.1. Does the reference support the claim?

3 out of 4

This reference received a score of 3, indicating that it offers moderate support for the claim. The evidence cited is a randomized controlled trial assessing the impact of nutrition counseling to treat moderate to severe depression. 67 adults suffering with major depressive episodes were randomized to receive either nutrition counseling (seven sessions) or social support for the same length and duration as the intervention group diet sessions. The trial lasted for 12 weeks.

Both groups improved depressive scores over the 12 weeks , but the diet counseling group had a significantly greater improvement in depressive symptoms compared with the control group receiving social support. The Pegan Diet states the intervention was “400 percent more effective than a typical Western diet.” This appears to refer to the proportion of participants experiencing remission in the intervention group (32.3%, n = 10), compared with the social support control group (8%, n =2). Such a claim is not appropriate based on the study design, as the control group were not given a Western diet, and received no dietary guidance. Therefore, the improvement in the diet intervention group cannot be interpreted as being more effective than a Western diet pattern.

Although this study provides support for the claim made, some aspects of the study limit the strength of the evidence, and none of these limitations were provided in The Pegan Diet, lowering the score given. For example, participants were not blinded (hidden from knowing which intervention they received). It is not unreasonable to suggest that the diet intervention group expected to improve as they were told beforehand that a healthy diet will help with their symptoms. The sample size was also smaller than planned, and with the lack of blinding this may have inflated the size of the effect of the diet intervention. Indeed, the effect size was very large, far greater even than the effect of anti-depressive medications on depression.

The authors also did not adjust their analyses for making multiple comparisons. They compared the two groups for many measures including depression and anxiety symptoms, wellbeing, diet and biomarkers, which can increase the chances of something showing up as ‘significantly different’ just by chance, and not because it really is different . For example, the significant difference in remission (32.3% vs 8.0%, p = 0.028), would be statistically non-significant if they had factored in the multiple comparisons.

Overall (average) score for reference accuracy

2.5 out of 4

Summary of the health-related intervention promoted in the book

The Pegan Diet recommends an inclusive, flexible diet based on the idea that food is medicine, combining aspects of a vegan diet and a paleo diet. The diet is intended as a long-term dietary change, and outlined through 21 principles.

The Pegan Diet recommends that 75% of our plate should be filled with a rainbow of colors from non-starchy vegetables. Guidance on carbohydrate-rich foods are typically provided as maximum intakes, whereas recommendations on fat-rich foods are typically provided as minimum intakes. For example, to consume up to 40g per day of starchy vegetables, up to 60g of whole grains, to avoid beans high in starch, to opt for beans low in starch, and to avoid gluten. Sugars and refined grains are to be limited, as well as fruit, which should be limited to one low-glycemic fruit portion per day. All sugar sweetened drinks and artificial sweeteners should be avoided. For fats, to consume 3-5 servings of healthy fats per day, opting for foods high in omega-3. Ideally, to consume fat at every meal, and consume a handful or two of nuts and seeds per day.

Organic plant foods, such as vegetables and grains, or organic animal-based foods, such as regeneratively raised, grass-fed beef and poultry or wild fish should be chosen, and conventional foods, such as factory-raised, grain-fed beef and poultry should be avoided. In general, dairy products should be avoided, but if consumed in moderation, full-fat or grass-fed options should be chosen over low-fat or conventional dairy products. Alongside the diet, there are recommendations to consume vitamin, mineral and omega 3 supplements.

Condition targeted by the book, if applicable

The Pegan Diet targets general health and a wide range of conditions and health outcomes, including heart disease, aging, dementia, weight gain, obesity, insulin resistance, type 2 diabetes, cancer, mood and autoimmune disorders.

Apparent target audience of the book

The Pegan Diet covers all ages. The majority of the book is aimed at a general audience, with a chapter on child nutrition from the ages of 6 months, and a chapter on aging aimed at older adults.

Criterion 3.1. Is the intervention likely to improve the target condition?

3 out of 4

The intervention received a score of 3, indicating that it is likely to moderately benefit the target condition, which is general chronic disease prevention. For the most part, the overarching guidance offered in The Pegan Diet for consuming vegetables, nuts, seeds and some fruit, whole grains, beans, and animal-based foods, while minimizing intakes of junk foods or sugar sweetened beverages would be expected to reduce the risk of chronic disease in most people relative to current Western dietary patterns. A fair amount of the guidance is roughly in line with health organization and government recommendations in terms of food groups to consume more of, and food groups to consume less of.

However, some of the advice may not improve the specific conditions mentioned and are either unnecessary or a cause for concern. For example, there is a recurring recommendation to limit foods high in sugar and starch. This is with the reasoning that sugar and starch are the primary cause of weight gain, obesity and insulin resistance, increasing the risk of further chronic diseases.

This advice is taken further by recommending restricting sugar and starch in those struggling with weight gain and poor metabolic health (which could be a significant proportion of readers). Limiting free sugar intake such as from sugar-sweetened beverages or added sugars in ultra-processed foods would likely be beneficial. However, complete sugar and starch elimination may not necessarily improve insulin sensitivity or achieve meaningful weight loss unless a sustained caloric deficit is achieved.

Restricting gluten, sugar, and starch may also limit intakes of multiple food groups beneficial for chronic disease prevention (e.g. beans, fruit, starchy vegetables and whole grains). There is a lack of strong evidence to suggest a benefit of avoiding gluten for the general population, outside of those suffering from celiac disease or gluten intolerance.

Some health claims are also overstated and more certain than the strength of current evidence would suggest. The recommendation to eat organic food and to avoid conventional food is unlikely to have a significant impact on general health outcomes within the context of the other recommendations made in The Pegan Diet. Whether individuals choose lean cuts of meat or opt for red meat, white meat or fish for their daily animal protein source may also influence saturated fat intake and the healthfulness of the diet. Although the book does not actively promote saturated fat intake, it does not point out that high saturated fat intake could be a problem.

The Pegan Diet also recommends some extreme, short-term restrictive dietary changes within some principles, including prolonged fasts, complete sugar and starch elimination, and a ‘10-Day Reset’ sugar detox, for which the scientific evidence that they benefit the health conditions mentioned is mixed or non-existent.

Criterion 3.2. Is the intervention likely to improve general health in the target audience?

3 out of 4

The intervention received a score of 3, indicating that it is likely to moderately benefit the general health of the target audience in the medium-to-long term (6+ months). As described in the previous section for Criterion 3.2., the general advice would be an improvement over current average diets in most countries.

The recommendation to consume 100-175g of animal meat twice per day may lead to red meat intakes above recommended daily limits, which may be associated with an increased risk of colorectal cancer and cardiovascular disease. This will depend on the types of animal meat chosen by the individual. But, in the context of the fiber- and nutrient-rich dietary pattern of The Pegan Diet, some risk is likely offset.

In addition to dietary change, The Pegan Diet recognises the importance of other lifestyle factors in reducing disease risk and improving health, as well as a chapter dedicated to the role of behavior change and habits for long-term change. The book promotes reducing chronic stress, getting enough sleep, not smoking, limiting alcohol and being physically active (e.g. pages 94, 114, 118 and 123), which all would be expected to improve general health.

Criterion 3.3. Does the diet portion of the intervention promote an adequate nutrient intake for general health in the target audience?

3 out of 4

The diet received a score of 3, indicating that it is likely to provide adequate nutrition for essential and nonessential nutrients for the general population in the medium-to-long term (6+ months). Generally, the guidance in The Pegan Diet would provide adequate intake of essential nutrients as well as intake of non-essential nutrients with health promoting properties (e.g. phytonutrients), by consuming a mixture of plant- and animal-based nutrient-dense foods (lots of non-starchy vegetables, nuts and seeds, meat, fish, eggs) and consuming fewer nutrient-poor foods (sugar sweetened drinks, ultra-processed foods high in added sugar).

For the most part, the majority of food groups can be consumed. But, there is nutritional variability that could be achieved on The Pegan Diet as it does provide some flexibility in its guidance, and for some individuals recommends complete elimination of sugar and starch. The strong advice to avoid dairy foods may also lead to difficulties in meeting certain micronutrient needs. Therefore, the nutritional adequacy can vary depending on how the advice is implemented.

The recommended use of vitamin and mineral supplements may be unnecessary given the recommendations to consume mostly nutrient-rich plant and animal foods. The Pegan Diet also promotes consumption of multiple sources of omega-3 (plant oils, nuts, seeds, oily fish, grass-fed beef) while also further encouraging an omega-3 supplement, which may add little additional health benefit.

Overall (average) score for healthfulness

3.0 out of 4