Everything Fat Loss: The Definitive No Bullsh*t Guide

Overall score

Scientific accuracy

Reference accuracy

Healthfulness

How hard would it be to apply the book's advice? Fairly easy

Book published in 2023

Published by BDCC Fitness

First Edition, Paperback

Review posted May 15, 2024

Primary reviewer: Shaun Ward

Peer reviewer: Matthew Carpenter

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

“The proportion of dietary carbohydrates and fats in the diet is not important for long-term weight loss”

Supporting quote(s) and page number(s)

[Page 185] “Just to reiterate this: if you keep your calorie intake the same and your protein intake the same, you can manipulate the ratio of carbohydrates to fats in your diet and the difference in body fat changes will only be a smidge or two above fuck all.”

[Page 185] “Therefore, it makes sense to choose [lower carb or fat diets] based on personal preference.”

[Page 187] “Keep in mind that the macronutrient ratio of your diet doesn’t mean much from a health perspective”

[Page 205] “There is no reason why you have to strive for a specific macronutrient ratio at all.”

[Page 205] “Rigidly sticking to the exact same macronutrient ratio every single day adds an additional dietary restriction rule which is unnecessary for most people.”

 

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

4 out of 4

This item received a score of 4, indicating that current evidence strongly supports the claim. Debates surrounding low carbohydrate and low fat diets for weight loss have dominated the health space for decades; however, most dietary trials comparing these dietary patterns do not report meaningful differences in long-term weight loss, which we define as 12 months or more for the purpose of this review.

One convincing line of evidence supporting this claim is meta-analyses of dietary trials investigating body weight changes at 12 months in response to low fat and low carbohydrate diets. We found five meta-analyses that met this criteria. Two of them reported no statistically significant differences in body weight change between low fat and low carbohydrate diets at 12 months. The remaining three meta-analyses found statistically significant differences in weight loss favoring low carbohydrate at this time point, with differences that are, in our opinion, not clinically meaningful (0.90–1.30kg difference in weight loss). One of these three meta-analyses also stratified the follow-up period beyond 12 months and found that the small benefit in favor of low carbohydrate diets was lost.

Another convincing line of evidence to support the claim is that lifestyle interventions achieving the most weight loss (≥10.0kg) at 12 months or longer are not exclusive to low carbohydrate or low fat diets. We found a few lifestyle interventions that achieved ≥10kg weight loss with diets ≥50% carbohydrate and ≤35% fat, and another few lifestyle interventions that achieved this amount of weight loss with diets ≤20% carbohydrates and ≥50% fat. We did not find that one particular macronutrient pattern had more published studies reporting large amounts of weight loss.

We acknowledge that one possible issue with weight loss studies, depending on the question of interest, is that they often implement rigid energy intake recommendations that do not necessarily reflect the ‘free-living’ nature of real life. This limitation could be used to hypothesize that a particular macronutrient pattern is superior in free-living conditions, even if not the case under rigid conditions with prescribed energy intakes. However, we could not find much evidence to support this. Three diet trials compared low carbohydrate and low fat diets without a calorie goal for 12 months, and all of them did not find a statistically significant difference in weight loss. Therefore, one macronutrient pattern is unlikely superior in free-living conditions either.

Overall, we tend to agree with the authors of a narrative review titled ‘The Data Behind Popular Diets for Weight Loss’, which stated that “Level of adherence to a calorie-restricted diet, rather than macronutrient content, is the driver of successful weight loss in the long term (>12 months).” The pursuit of the ideal macronutrient content diet is reductionist and can hide the more critical component of dietary interventions for weight loss: sustainable behavior change. Just like medical therapies, diet interventions should only be expected to be effective when treatment is active. It is surprisingly rare for diet trials to assess levels of dietary adherence and then measure it against the degree of weight loss, but the studies that do have consistently noted that increased adherence is associated with greater weight loss. Strikingly, a recent systematic review evaluated 12 prospective dietary intervention studies in people with overweight or obesity and reported that “…all the studies reviewed in this systematic review disclosed that adherence to prescribed diets was a vital determinant of weight loss and obesity management and treatment.”

Overall (average) score for claim 1

4 out of 4

Claim 2

“There is no one-diet-fits-all for weight loss”

Supporting quote(s) and page number(s)

[Page 15] “Weight loss advice shouldn’t be a one size fits all”

[Page 172] “On the contrary, I think it should be seen as a positive that there is no one-size-fits-all diet that people should follow”

[Page 16] “Put simply, a plan that works really well for one person could be disastrous for another person.”

[Page 71] “Your individual circumstances are highly personal so it makes no sense to think you should all follow the same diet and training plan and expect any reasonable level of success.”

[Page 361] “The problem [with weight loss/gain] is, there isn’t a universal solution.”

[Page 362] “Complex issues require nuanced solutions and my goal in writing this book was to present you with a menu of options in an unbiased fashion, so you can pick and choose any principles you want to adopt, while also being empowered with the knowledge to reject others that you don’t.”

[Page 363] “That’s the beauty of there being a no one-size fits all approach when it comes to weight management”

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

4 out of 4

This item received a score of 4, indicating that current evidence strongly supports the claim.

Weight loss can be achieved via diets that emphasize different macronutrients and foods. In a review of 14 popular diets, all of them reported average weight loss of 0.31–7.77kg versus control diets at 6 months and, other than one, 12 months (1.28–9.86kg). These diets ranged from the Atkins diet, which emphasizes eating animal foods, to the Ornish diet, which emphasizes eating mostly plants. Other diets that have reported 12-month weight loss include caloric restriction (tracking and restricting calorie intake), intermittent fasting (eating within an 6–8 time window) and total diet replacement (consuming only very low-calorie formulas such as soups and shakes). There are clearly a range of different diets at people’s disposal that provide an average weight loss benefit (at least up to 12 months), even if they each do not necessarily cause weight loss for everyone.

Expanding on our point about the importance of dietary adherence in Claim 1, we again consider this factor to be a key reason why diets may cause long-term weight loss for some people and not others. Not everyone finds the same diet easiest to stick to. Many scientific reviews have described that people have different genetic predispositions, learned food preferences, neophobias (tendency to try unfamiliar foods), allergies and intolerances, and cultural and social considerations, that ultimately converge to determine eating behavior and how feasible it is for dietary habits to change. As one example, a weight loss diet may require people to buy foods they cannot access or afford, equipment they do not own, and time for preparation and cooking they cannot prioritize. All of these factors inform the development of personal systems for making—and sustaining—food choices, which are likely to differ from one person to another.

To further this point, we note that a couple of long-term diet studies have reported individual weight loss outcomes and found tremendous variation even within the same diet. One example is the DIETFITs study, which investigated the effects of low-carbohydrate and low-fat diets for 12 months. Another is the POUNDs trial, which investigated weight loss in response to energy-restricted diets with four different macronutrient compositions. In both of these studies, the average weight loss was between 6.9–7.5kg at 12 months in all diet groups, but they all had some participants losing 20–30kg and other participants gaining 5–10kg. We can therefore infer the claim in Everything Fat Loss that there is no one-diet-for-all solution for weight loss, as not everyone assigned to a successful weight loss diet actually loses body weight, and some participants gain body weight.

Though we cannot know with certainty why individual outcomes vary so much within diet groups (and whether the variation is significantly more than control), it is likely that differing levels of adherence impact individual results. In DIETFITs, for example, participants with greater levels of adherence and diet quality reduced their BMI the most, regardless of whether they were in the low carbohydrate or low fat group. The interaction between diet adherence and weight loss was not reported in the POUNDs trial; however, similar findings have consistently been reported elsewhere. That is, the level of dietary adherence, regardless of the type of diet, predicts participants’ success in losing and maintaining body weight. It could be argued that some diets are inherently easier for people to adhere to than others, but we consider it highly implausible, if not objectively wrong, that everyone is able to adhere well to the same weight loss diet. Therefore, we believe the evidence supports the book’s claim that there is not a one-diet-for-all solution to weight loss.

Overall (average) score for claim 2

4 out of 4

Claim 3

“Weight loss diets have psychological risks”

Supporting quote(s) and page number(s)

[Page 8] “Even without the terrible crash diets, a lot of dieting practices come with potential psychological risks.”

[Page 9] “Not everyone who loses weight is healthier, happier, and more confident than they were”

[Page 9] “There have been also been many times when a client has been seeking fat loss and I have actively advised against it”

[Page 9] “Some people would do better not striving to achieve fat loss at all, yet you rarely hear anyone talk about this.”

[Page 9/10] “Contrary to what many people think, the science around fat loss is not limited to what diet plan works best. It includes the psychology of what is sustainable in the long term, the factors that influence how much food someone wants to eat, the possible physical and psychological side effects of haphazard dieting and many other complex topics.”

[Page 13/14] “The problem with striving to simply ‘look better’, as opposed to working towards clearer and more focused goals, is that it has the potential to negatively impact the way you feel about yourself and, in turn, nudge you towards weight loss strategies that aren’t a good idea. ”

[Page 15] “Weight loss is a very broadly applied goal and while it may be considered as health-promoting for someone with a high body weight or a benign endeavour for other people, there are risks involved which may be amplified if someone tries to lose weight via any means necessary.”

[Page 16] “Person B is seeking an exclusively aesthetic goal that may actually come with sacrificing their health, at least temporarily.”

[Page 23] “In the same way that some people become so focused on earning more money that they work themselves into the ground, sacrifice quality time with their loved ones and feel miserable, being fixated on dieting comes with risks.”

[Page 23] “What if you followed a diet plan and found yourself uncontrollably binge eating at weekends?”

[Page 25] “Dieting is often idealised as a solution for you to improve your health, happiness and confidence but in reality, a lot of diet books are not designed to prioritise these at all, they are just hyper-focusing on your body composition in isolation and conveniently disregarding everything else”

[Page 26] “If your goal is to improve your health, losing weight can sometimes contribute to that but it can also come with risks. Many people lose weight at the expense of their health, like being trapped in a yo-yo cycle of hopping between overly restrictive crash diets”

[Page 31] “If your only goal is to lose body fat, it is possible you will inadvertently sacrifice your own quality of life to get there.”

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

2 out of 4

This item received a score of 2, indicating that current evidence weakly supports the claim. As ‘psychological risks’ is a broad term, we decided to base our scoring for this claim on how weight loss diets affect common psychological symptoms (e.g. mood, vitality, and social functioning), binge eating, and health-related quality of life (HRQoL). By ‘weight loss diets’, we referred to diets intended to create an energy deficit and support weight loss.

For common psychological symptoms, some evidence links them with severely energy-restricted diets, such as the Minnesota starvation experiment in 1944. Participants were subject to 50% energy restriction for 6 months and, based on known reports, suffered from irritability, intense preoccupation with thoughts of food, loss of sexual drive, and social introversion. The low energy intake was thought to be a major contributing factor to these issues. It’s important to note that participants started out lean, and became emaciated during the course of the study, so its relevance to typical weight loss scenarios is unclear.

A more recent example is the DiRECT trial, which was an intensive weight management program that included a 12–20 week diet replacement phase with a very low energy intake (810kcal/day). During this period, 13.7–46.8% of participants experienced cold sensitivity, headache, dizziness, fatigue, and mood changes.

The limitation to these studies, however, is that symptoms were not reported at baseline or in control groups; therefore, we cannot be certain these diets increased the prevalence of these symptoms, and, if they did, to a degree that would be considered a psychological risk. These are also highly restrictive diets not representative of typical diets that people commonly attempt for weight loss, so it is difficult to extrapolate the findings to the real world.

The literature overall is not particularly concerning for weight loss diets and common psychological symptoms. In a systematic review of 17 behavioral intervention studies (16 that included dietary restriction) and a meta-analysis of 35 total diet replacement studies, a significant improvement in vitality and/or social functioning was reported pre- to post-diet. We also found a 12-month study and 24-month study of more moderate energy restriction (25% energy deficit) that both reported no significant detriments in mood compared with control diets. Therefore, although we agree that common psychological symptoms on weight loss diets are possible—they are not benign interventions—evidence to support modest energy restriction as problematic is pretty thin and unconvincing. It is possible that for many people, the health benefits of losing body weight may counter any common psychological symptoms that may otherwise be associated with energy restriction.

In terms of binge eating disorder, most evidence that reports a significant association with weight loss diets is cross-sectional and has little to say about whether one causes the other. That is, whether weight loss diets cause binge eating disorder, or if people with binge eating disorder are more likely to engage with weight loss diets.

We only found a few prospective studies (which follow people over time), restricted to adolescent populations, that reported that going on weight loss diets predicted the development of new eating disorders (including binge eating disorder). However, these seem to be the exception, not the norm. Three systematic reviews, one including a meta-analysis, concluded that most obesity treatments with a dietary component were either neutral or beneficial for binge eating in children or adolescents.

In adults, we found similar evidence. One systematic review found a beneficial effect for binge eating in all dietary energy restriction studies assessing adults with binge eating disorder at baseline, and mixed results for adults without binge eating disorder. A recent systematic review with a meta-analysis also concluded that behavioral weight loss interventions (including energy restriction) in adults with overweight or obesity consistently reduced global eating disorder risk, binge eating severity, and binge eating episodes. Interestingly, none of the 49 trials assessed, including those with severe energy-restricted diets (ranging from 420–2000 kcal per day), found an increase in any measure of disordered eating, including binge eating.

An important note here is that most of the prospective weight loss studies we found for binge eating were either professionally administered and/or clinically supervised and/or paired with other behavioral therapies, which could greatly reduce the risk of binge eating when starting a weight loss diet. We understand that, in the real world, many people start weight loss diets without professional support, which could in theory increase the risk for disordered eating.

Finally, in terms of HRQoL (summarizing self-perceived physical, psychological, and social health), we again found a lack of prospective evidence that weight loss diets worsen outcomes. In people with overweight or obesity, energy-restricted diets, as well as low fat and low carb diets, tend to report either a neutral effect or benefit to HRQoL. For example, in a systematic review of 17 behavioral intervention studies lasting at least 10 weeks, 16 of which included dietary restriction, a consistent improvement in HRQoL was reported. Similarly, a systematic review of 24 meta-analyses of total diet replacement studies, which are usually very low-energy interventions, found no marked adverse effects of these programs on any facet of mental well‐being (including depression, anxiety, stress, vitality, etc.) in adults with overweight or obesity.

The type of studies indicating the most concern for psychological risks are those on weight cycling. Specifically, some evidence suggests that people with a higher frequency of weight cycling (that is, people who attempt weight loss more frequently) are more likely to have depressive symptoms, independent of BMI. This could suggest that engagement with weight loss diets poses some longer-term issues for certain people, at least when there are frequent unsuccessful attempts to lose weight.

However, even if true, the blame should not necessarily be put on weight loss diets themselves. Without controlled studies, it is extremely challenging to tease out the effect of the diet versus the environment in which one felt compelled to undertake the diet, and the social pressures of succeeding or failing a weight loss attempt. Elements of anxiety and depression are likely paired with stagnant weight loss progress despite good intentions, and also the pressure to avoid negative perceptions based on weight. But, at least based on current evidence, there is not much to show that the people reporting issues with weight cycling would have better psychological health if they had never engaged with a weight loss diet.

We also have to be mindful that the baseline risk of psychological issues, such as depression, is not zero without weight loss diets. People with obesity have higher odds of depressive symptoms than people with a lean BMI, an effect that may be at least partially explained by systemic inflammation and obesity-related morbidity, not necessarily more frequent weight loss attempts.

Overall, the literature only weakly supports that weight loss diets have psychological risks. Common psychological symptoms due to severe energy restriction and depressive symptoms due to weight cycling have been reported, but the supportive studies are intrinsically unconvincing of a cause-and-effect relationship in typical weight loss scenarios. Most high-quality studies report a neutral or beneficial effect of weight loss diets on most components of psychological health.

Overall (average) score for claim 3

4 out of 4

Overall (average) score for scientific accuracy

3.3 out of 4

Reference 1

Reference

Chapter 1, reference 19. Barry VW et al. Prog Cardiovasc Dis 56(4):382–390. 2014.

Associated quote(s) and page number(s)

Page 22: “For example, one meta-analysis (think of this as a statistical analysis of multiple research studies pooled together) concluded that compared to ‘normal weight-fit’ individuals, those with low levels of cardiorespiratory fitness had twice the mortality risk regardless of their BMI. Those who were classed as fit but having obesity appeared to have a similar risk of death as people who were fit but with a ‘normal’ body weight.”

Criterion 2.1. Does the reference support the claim?

4 out of 4

This reference scored 4, indicating that it strongly supports the claim. It was a meta-analysis of 10 prospective studies that assessed the association between cardiorespiratory fitness, body mass index, and all-cause mortality. Cardiorespiratory fitness and BMI categories were combined to make 5 comparison groups (i.e., normal weight-unfit, overweight-unfit, overweight-fit, obese-unfit, and obese-fit) and a referent group (i.e., normal weight-fit). Compared to normal weight-fit individuals, unfit individuals had twice the risk of mortality regardless of BMI. Overweight-fit and obese-fit individuals had similar mortality risks as normal weight-fit individuals.

We will mention, however, that 7 of the 10 studies in this meta-analysis used a definition of ‘fit’ that is highly questionable. Specifically, they considered all participants in the 2nd to 5th quintile (fifths) of cardiorespiratory fitness as fit, with only the 1st quintile defined as ‘unfit’. This categorization method may not fairly differentiate between fit and unfit individuals and may explain why no statistically significant differences in mortality risk were found between these categories.

Reference 2

Reference

Chapter 11, reference 4. Westerterp KR et al. Nutr Metab 1(1):5. 2004.

Associated quote(s) and page number(s)

Page 271: “It may also be interesting to know that alcohol has a thermic effect estimated at 10–30%, meaning your body will actually burn more energy after consuming it than it would for carbohydrates and fat.”

Criterion 2.1. Does the reference support the claim?

4 out of 4

This reference scored 4, indicating that it strongly supports the claim. It was a review of the measuring conditions and dietary characteristics of 15 studies that investigated diet-induced thermogenesis (heat production associated with digesting food and beverages). Within this pool of studies, the two that investigated alcohol as a contributor to total energy intake support the claim. One of these studies compared an alcohol-free diet to an energy-matched mixed diet with 22% of energy from alcohol. The alcohol-inclusive diet increased diet-induced thermogenesis from 7.2–8.6% (a relative 19% increase). The other study was similar, comparing three alcohol-free diets to an energy-matched diet with 23% of energy from alcohol. The diet with alcohol had the highest overall diet-induced thermogenesis of 9.0%, compared with the alcohol-free diets that ranged between 7.1–8.0% (a relative 13–27% increase). This data led the review’s author, Kevin Westerterp, to state, “In conclusion, the main determinants of diet-induced thermogenesis are the energy content and the protein-and alcohol fraction of the diet.”

Reference 3

Reference

Chapter 8, reference 22. Kirkpatrick CF et al. J Clin Lipidol. 13(5):689–711. 2019.

Associated quote(s) and page number(s)

Page 180: “The actual threshold for what is ‘low’ can vary wildly as well, ranging from less than 10% for very-low-carbohydrate or ‘ketogenic’ diets to anything up to 45% of your calorie intake.”

Criterion 2.1. Does the reference support the claim?

4 out of 4

This reference received a score of 4, indicating that it strongly supports the claim. The reference was a scientific statement from the National Lipid Association Nutrition and Lifestyle task force, covering the evidence and clinical recommendations on low-carbohydrate diets (including ketogenic) for managing body weight and cardiometabolic risk factors. In this statement, the authors agree with Everything Fat Loss that the terminology and definitions used in the literature on carbohydrate-restricted diets vary considerably. Their review considered <10% total energy intake as a very-low-carbohydrate diet, and 10–25% total energy intake as a low-carbohydrate diet. This is slightly less than the range stated in Everything Fat Loss; however, the book supported the same claim with another systematic review and meta-analysis that did define a low-carbohydrate diet as <45% total energy from carbohydrates.

 

Reference 4

Reference

Chapter 13, reference 34. Laitner MH et al. Eat Behav 21:193–197. 2016

Associated quote(s) and page number(s)

Page 320: “By now, you probably have a pretty clear idea that there is a significant amount of research supporting the association between self-monitoring your food intake and better weight loss and weight maintenance outcomes, hence earning the title of being a ‘cornerstone’ or ‘core component’ of behavioral weight loss treatment”

Criterion 2.1. Does the reference support the claim?

4 out of 4

This reference received a score of 4, indicating that it strongly supports the claim.

This study was a post-hoc analysis of the Treatment of Obesity in Underserved Rural Settings study, a randomized controlled trial designed to explore the effectiveness of three extended-care programs on sustained weight loss in 167 patients with obesity. All patients completed a lifestyle intervention, including daily self-monitoring of food intake for 6 months (Phase 1), before random assignment to one of three extended-care programs lasting 12 months (Phase 2). At the end of phase 2, patients were categorized into one of three clusters depending on the amount of weight lost in both phases: low success (approx. 2.0–4.5kg weight loss), moderate success (approx. 5.0–11.5kg weight loss) and high success (approx. 14.0–21.5kg weight loss). The different clusters were then analyzed based on self-monitoring frequency during each phase.

A key result was the significant difference in food self-monitoring frequency between all three groups during Phase 2. More food self-reporting was associated with more weight loss. In Phase 1, the reason this was not the case was due to a lack of difference in food self-monitoring between the moderate and high success groups; there were still differences in food self-reporting between the low success and high success clusters—19 and 106 fewer food records in Phase 1 and Phase 2, respectively.

To add, Everything Fat Loss provided six more references to support that “a significant amount of research…” has reported an association between self-monitoring food intake and better weight loss/maintenance outcomes. The claim did not rely on this study alone.

 

Reference 5

Reference

Chapter 11, reference 20. Vatsalya V et al. Alcohol Clin Exp Res. 36(2)207–213. 2012.

Associated quote(s) and page number(s)

Page 278: “One trial examined hormonal responses to intravenous alcohol and noticed that testosterone suppression was seen primarily in males, not females, and this might also change depending on their age”

Criterion 2.1. Does the reference support the claim?

4 out of 4

This reference received a score of 4, indicating that it strongly supports the claim.

This was a randomized, placebo-controlled crossover study where participants received either infusions of alcohol or saline/placebo to achieve and maintain breath alcohol concentrations of 50 mg% (or 0 mg% with saline/placebo).

The results showed that only young males decreased their free testosterone levels (-11.20 pg/mL) in response to alcohol; younger women, and younger and older men, increased free testosterone by 0.04–3.49 pg/mL compared with baseline values. The change in free testosterone showed a significant interaction between treatment and baseline testosterone levels. Since males had a considerably higher baseline testosterone, this indicated that alcohol-induced suppression of testosterone occurred predominantly in men. The authors concluded that “Acute alcohol administration resulted in changes in gonadal hormones that differed by sex.”

Reference 6

Reference

Chapter 12, reference 6. Hagmar M et al. Clin J Sport Med. 23(3):197–201. 2013. 

Associated quote(s) and page number(s)

Page 287: “One study took male Olympic athletes and divided them into groups based on whether their sport emphasized having some level of physical leanness, such as boxing, judo, wrestling and so on. The researchers found that lean athletes had significantly lower leptin levels on average”

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. This was a cross-sectional study of 44 Swedish male Olympic athletes participating in 26 different sport disciplines. The athletes were divided into 2 groups based on whether their sporting discipline emphasized leanness or not, and their blood levels of various hormones were analyzed. The 18 athletes in sports that emphasized leanness athletes displayed significantly lower serum levels of leptin than the 26 athletes in sports emphasizing nonleanness (1.03 ng/mL vs 1.66 ng/mL).

Reference 7

Reference

Chapter 9, reference 9.  Arciero PJ et al. Obesity. 21(7):1357–1366. 2013.

Associated quote(s) and page number(s)

Page 245: “One study tested the impact of adjusting meal frequency in combination with a high-protein diet, dividing its participants into three groups.

1. Higher protein intake (35% of total calorie intake) eating three meals per day
2. Higher protein intake (35% of total calorie intake) eating six meals per day
3. Traditional protein intake (15% of total calorie intake) eating three meals per day

After a brief introductory baseline period, all participants went through two different phases – one where they consumed enough calories to maintain their body weight and a second phase where they reduced their intake by 25% to promote weight loss. Results-wise, both high protein diets were better for regulating hunger than the traditional protein diet, suggesting higher protein intakes are important regardless of meal frequency. From a body composition perspective, a high protein diet consumed as six meals per day was better for increasing lean body mass and decreasing abdominal fat than when it was consumed as three meals per day.”

Criterion 2.1. Does the reference support the claim?

3 out of 4

This reference received a score of 3, indicating that it moderately supports the claim.

This was a controlled trial of 30 overweight individuals, randomized into three dietary interventions lasting 56 days. All of the information in the book about the dietary interventions in this study is correct, as is the result of changes in lean body mass. However, the results for hunger and abdominal fat are not entirely accurate.

For hunger, while it is true that hunger ratings were significantly greater for traditional protein compared with higher protein groups, this was only the case during the second phase of the dietary intervention, when participants were in a 25% energy deficit (shown in supplementary table 4 of the study). Hunger was still slightly higher in the traditional protein group in the caloric maintenance phase of the study, but the differences were not statistically significant. Feelings of fullness and the desire to eat were also not significantly different between groups at any point in time during this study.

For abdominal fat, the high-protein group eating 6 meals per day indeed lost significantly more abdominal fat at day 57 compared with the traditional protein group. But losses compared with the high-protein group eating 3 meals per day were not statistically significant (both groups lost between 0.4–0.6kg of abdominal fat from baseline).

Reference 8

Reference

Chapter 6, reference 5. Moreno-Agostino D et al. Int J Behav Nutr Phys Act. 17(1):92. 2020.

Associated quote(s) and page number(s)

Page 131: “Therefore, we shouldn’t be surprised that the potential health benefits of exercise are vast and diverse, including…slowing down the decline of health and functioning associated with age.”

Criterion 2.1. Does the reference support the claim?

4 out of 4

This reference scored 4, indicating that it strongly supports the claim.

This study analyzed the Ageing Trajectories of Health: Longitudinal Opportunities and Synergies (ATHLOS) project, which harmonized data from 17 cohort studies and investigated trajectories of healthy aging (over at least 10 years) and the potential determinants of rapid aging. The researchers categorized the 130,521 total participants as physically active or not based on self-reported lifestyle questionnaires, and ‘healthy aging’ was determined by a score based on a relevant WHO framework. Participants were then categorized as displaying either a high stable level of health throughout the whole study period (high stable; 71.4% of the sample), a low baseline level of health with minimal change across the follow-ups (low stable; 25.2% of the sample), or baseline health similar to the high stable class with severe health deterioration over time (fast decline; 3.4% of the sample).

The primary result was that engagement in any level of physical activity was associated with 82% and 56% reduced odds of being in the low stable and fast decline trajectories groups, respectively, compared with the high stable trajectory group. These results were replicated with alternative ways of defining physical activity and, in sensitivity analyses, using reduced samples. The researchers concluded that “Our findings suggest a positive impact of physical activity on healthy aging, attenuating declines in health and functioning.”

Reference 9

Reference

Chapter 10, reference 19. Holt SA et al. Eur J Clin Nutr. 49(9):675–690. 1995.

Associated quote(s) and page number(s)

Page 263: “In the ‘satiety index’ study that gave participants 240-calorie portions of individual foods before waiting two hours to see how much they would eat afterwards, many foods that are high in sugar scored very low, indicating they were not great at appetite regulation. Mars Bars, cake, croissants, doughnuts and ice cream all ranked poorly. So we can conclude that sugar is easy to overeat, right? Well, when we look at the unprocessed foods that were measured – bananas, grapes, apples and oranges – which also contain sugar, they all scored better. So is it sugar that isn’t very filling or is it the combination of sugar and fats manufactured into specifically designed delicious little packages that is the problem? Satiety scores were inversely related to how palatable a food was: the tastiest items are normally the ultra-processed ones and they also tend to be worse for appetite regulation.”

Criterion 2.1. Does the reference support the claim?

3 out of 4

This reference scored 3, indicating moderate support for the claim.

The book’s information about the study methodology is correct; however, satiety was measured by two methods, not just one. The first method was with a satiety index score (labeled as a ‘subjective satiety response’), calculated every 15 minutes after eating each test food and expressed as a percentage of the satiety value of white bread. The second method was an ad libitum meal 120 minutes after the test food was consumed, when the researchers measured how much subjects ate from a range of standard foods and drinks.

As the book correctly mentioned, the food group with the highest average satiety index score was fruit (170% of white bread), despite containing the most sugar. In addition, a significant inverse correlation was found between the palatability ratings and satiety index scores: more palatable foods were generally less satiating.

However, this study did not directly show that “the tastiest items are normally the ultra-processed ones” or that the level of food processing had anything to do with the satiety score index or the amount eaten two hours after the test food. Food processing was not considered in the study results, and the food components that did correlate with satiety index scores (protein, fiber, fat, and water) may have been independent of food processing. Popcorn, all-bran, baked beans, and wholemeal bread are considered ultra-processed food but had similar satiety index scores to fruit.

We also think this study’s strength is weakened by recruiting 11–13 subjects to test each food group (41 participants in total), with most participants testing only one food. This type of study benefits tremendously from a crossover design, where every participant tests all foods and is their own control.

Reference 10

Reference

Chapter 4, reference 6.  Placeholder et al. Am J Epidemiol 5:236. 1997.]

Associated quote(s) and page number(s)

Page 96: “However, as our environment slowly nudges us more and more towards sedentary lifestyles, fewer of us are meeting general physical activity guidelines. For example, one study looked at the data of nearly 2 million participants across 168 countries and estimated that globally, more than a quarter of all adults were insufficiently active”

Criterion 2.1. Does the reference support the claim?

4 out of 4

This reference received a score of 4, indicating that it strongly supports the claim.

The study pooled data from 358 population-based surveys that reported the prevalence of insufficient physical activity between 2001–2016. Less than 150 minutes of moderate-intensity and/or 75 minutes of vigorous-intensity physical activity per week was defined as insufficient physical activity, as per the World Health Organisation guidelines. The global age-standardized prevalence of insufficient physical activity was 27.5% in 2016, aligning with the Everything Fat Loss claim.

We will add that certain regions in the world had less than a quarter of adults labeled as insufficiently active in 2016: Central and Eastern Europe (23.5%), Sub-Saharan Africa (21.4%), East and Southeast Asia (17.3%) and Oceania (16.3%). As physical activity varied widely across countries (from 5.5% in Uganda to 67.0% in Kuwait) and was most common in high-income countries, this may infer that environmental shifts contribute to sedentary lifestyles.

Overall (average) score for reference accuracy

3.8 out of 4

Summary of the health-related intervention promoted in the book

Everything Fat Loss openly states upfront that it does not intend to offer a new fat loss diet or promote an existing one. Ben Carpenter says throughout the book that successful weight loss diets will be different for everyone and there is no one-size-fits-all approach. That being said, we did pick up on several themes and non-mandatory suggestions in the ‘How can you put this into action?’ sections of the book, that is likely to be perceived as direct advice. We have therefore used these suggestions to form a health intervention that we can critique, for the sake of this review. These suggestions include:

•         Prioritize nutrient-dense and minimally-processed foods (page 109/137/211/218/229)
•         Lower the energy density (fewer calories per gram) of the diet (page 105/262)
•         Do not strictly avoid any particular food (page 232/236)
•         Prioritize daily moderation over ‘cheat meals’ and ‘cheat days’ (page 296)
•         Minimize consumption of sugar-sweetened beverages (page 266)
•         Restrict access to highly palatable foods that are easy to overeat (page 52/79)
•         Consume adequate protein (page 186)
•         Drink alcohol responsibly and occasionally, if at all (page 280/281)
•         Personal preference guides dietary fat and carbohydrate intake (page 186/187)
•         Consider having fewer distractions and being more mindful while you are eating (page 355/360)
•         Implement some form of food tracking unless it causes stress (page 336)
•         Focus on diet more than exercise for weight loss, but ideally do both (page 143)
•         Implement fasting if it helps you control hunger and overall food intake (page 205)

In addition, regardless of the diet discussed, Everything Fat Loss encourages the consumption of ample fruits and vegetables, and the restriction of added sugars, refined carbohydrates, trans fats, and processed meats (page 109/137/187/211/218/229). For omnivorous diets, fish, eggs, and lean meats are recommended. For higher carbohydrate diets, legumes and wholegrains are recommended. For lower carbohydrate diets, nuts, avocados, and extra-virgin olive oil are recommended.

Condition targeted by the book, if applicable

Overweight and obesity

Apparent target audience of the book

The target audience of Everything Fat Loss is anyone interested in losing weight.

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

4 out of 4

The guidance provided in Everything Fat Loss received a score of 4 out of 4, meaning it will likely result in substantial weight loss in people with overweight and obesity in the short to medium term. Despite the book not recommending a rigid intervention, the book recommends a variety of diets that, as we clarified in response to claims 1 and 2 of the Scientific Accuracy section, have at least moderate amounts of evidence for weight loss in the short to medium term.

The majority of the tools and strategies that Ben Carpenter encourages are also backed with at least moderate amounts of evidence (e.g. dietary tracking, eating with fewer distractions, and restricting access to highly palatable foods that are easy to overeat). We did not consider any practical tips in the book to be unreasonable or extreme.

In addition, diets composed of mostly minimally processed and low-energy density foods, as Ben recommends, are generally associated with weight loss. He clarifies these foods can be implemented within a number of diets that tend to cause weight loss in people with overweight and obesity (e.g. low-fat, low-carb, plant-based, Mediterranean).

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

4 out of 4

The intervention received a score of 4, indicating it is likely to greatly improve the health of the target audience. The book does not promote a specific intervention or popular named diet, but its general advice, which can apply to most diets, is far healthier than the standard western diet. The guidance offered in the book aligns strongly with current dietary guidelines in the United States, United Kingdom, and Canada, which we consider to be mostly reasonable, scientifically sound, and healthier than people’s typical eating patterns. From a health perspective, we are not concerned with any of the dietary advice mentioned in the book.

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

4 out of 4

The diet received a score of 4, indicating that it is probably nutritionally adequate. The book recommends eating all of the most nutrient-dense foods (fruits, vegetables, meat, fish, eggs, dairy, legumes, nuts, seeds, and wholegrains) and restricts only nutritionally poor foods (sugar-sweetened beverages, refined grains, processed meats, and common ‘junk’ foods). The book recommends avoiding very low-calorie diets and aiming for gradual weight loss, which should further reduce the risk of nutritional deficiencies when eating these foods.

Overall (average) score for healthfulness

4 out of 4