I woke up to a tempest in a teapot on Sunday.
Two days prior, we had published a review of the book Metabolical. Sunday morning UK time, the primary reviewer Sam Dicken published a thread on X summarizing the review. Six hours later, carnivore diet advocate Shawn Baker reposted one of Sam’s posts with the following comment:
These are the people that are literally killing you!
Low-carb diet advocate Ken Berry soon followed with an abusive comment toward Sam. Many others then piled on, resulting in hundreds of abusive comments toward Sam and Red Pen Reviews.
What’s the outrage about?
The fuss was about a single bullet point in the summary of our review of Metabolical:
We think the book’s diet recommendations are an improvement over how most people eat, but the guidance is vague. Avoiding all processed foods could lead to problems such as nutrient deficiencies in some people, and high intake of some “Real Foods” may also cause problems (e.g. red meat).
As far as I can tell, they interpreted this as an endorsement of ultra-processed food, and a claim that ultra-processed food is healthier than red meat.
As I’ll explain, this interpretation is wrong. Although the bullet point does leave room for interpretation, and that’s on us, the misunderstanding could have been avoided by scrolling past the summary and reading the healthfulness section of the review.
What does the bullet point mean?
The bullet point explains our scoring for criterion 3.3, which scores for the following question: Does the diet portion of the intervention promote an adequate nutrient intake for general health in the target audience? Metabolical received a 2 out of 4, which in this context means that its profile of essential and non-essential nutrients is a bit better than typical diets.
Please keep in mind that this score is specifically about nutrient adequacy, not about the impact of the diet on obesity, type 2 diabetes, or general health, which the book received a higher score for (3 out of 4 for criteria 3.1 and 3.2).
The bullet points at the top of our reviews are our attempt to summarize much longer and more nuanced points in the full review. In this case, the full argument can be found in the expanded healthfulness scoring section of the review page.
The argument is as follows:
- “Processed food” can refer to a wide variety of things. Depending on the definition, it can include canned beans, olives, cheese, tofu, butter, bacon, whole wheat bread, iodized salt, Twinkies, and Cheetos (the commonly-used NOVA definitions are here). Metabolical says to completely avoid processed food, but it doesn’t provide a clear or consistent definition of the term. The advice could therefore be interpreted very differently by different readers.
- Processed food makes a large contribution to vitamin and mineral intake in the US and other wealthy countries. Keep in mind that “processed food” doesn’t necessarily mean the ultra-processed foods that people often think of when they hear that term. It includes many traditional foods like those listed above, some of which are healthy.
- While most people will not run into any problems eating only minimally processed foods, including some processed foods in the diet can help certain vulnerable groups meet nutritional needs. For example, fortified foods may help elderly people with low calorie intake and poor micronutrient absorption meet their needs for vitamins and minerals.
- Metabolical provides very little guidance about what specific foods to eat. The fact that a person is eating minimally processed food doesn’t guarantee a nutritionally adequate diet. For example, the nutrient analysis of a nose-to-tail carnivore diet we did in our review of The Carnivore Code suggests that it’s inadequate for several essential nutrients, despite being a minimally processed diet. Likewise, a vegan diet of minimally processed foods is nutritionally inadequate without supplementation. Most people eating a varied diet will be fine with a little common sense, but as written, the book’s guidance leaves room for nutritional inadequacy in some scenarios.
As you can see, this is not an endorsement of ultra-processed foods at all, nor is it an argument that ultra-processed foods are healthier than red meat. If the book had clearly and consistently stated to avoid ultra-processed foods specifically, or provided another definition of the word “processed” that better differentiates between health and unhealthy foods, we would have agreed that this is supported by the evidence.
The review states that we think the book’s recommendation to avoid all processed food is healthier than how most people currently eat, despite the lack of specific guidance. This is reflected in the book’s healthfulness score of 67%. For reference, the typical highly processed diet in affluent countries would receive a healthfulness score of 25% (1 out of 4 for all three healthfulness criteria).
Our response
The first thing I want to clarify is that our job at Red Pen Reviews is not to cater to peoples’ beliefs about nutrition, nor is it to cater to social media outrage. Our reviews will inevitably upset some people, and that’s OK. Our job is to get as close to the truth as possible. Some of our conclusions are uncertain and can be debated, but we document our methods, reasoning, and citations so people can make up their own minds about our work.
We understand that people and diet tribes will attack Red Pen Reviews sometimes, but we will not be intimidated by it. If they want to put down their pitchforks, the door is always open to constructive and respectful feedback.
That said, we do think the bullet point in our review summary could be misunderstood even by some people reading it in good faith. Given that, it makes sense to reword it. We’ve changed it to the following:
We think the book’s advice to focus on minimally processed food is an improvement over how most people eat, but since the book provides little guidance on what specific foods to eat, it leaves some potential for inadequate nutrient intake.
We’ve also added a bit of detail to the healthfulness section of the review to reduce the risk of misinterpretation. We continue to stand by the book’s healthfulness scoring.
The big picture
This situation illustrates the extreme beliefs and behaviors that characterize some modern diet tribes, similar to what we see in politics. This is obviously a problem, and one we don’t have a solution for at Red Pen Reviews. However, in this time of polarizing soundbites and misinformation, we think it’s especially important to have resources like Red Pen Reviews that evaluate information according to a structured method that maximizes informativeness, consistency, and transparency, while minimizing bias.