The Metabolic Typing Diet Book Review

Recently, I finished reading The Metabolic Typing Diet by William Wolcott and Trish Fahey. For those who haven’t read it, here’s a general summary which was written on

For hereditary reasons, your metabolism is unique. Cutting-edge research shows that no single diet works well for everyone–the very same foods that keep your best friend slim may keep you overweight and feeling unhealthy and fatigued. Now, William Wolcott, a pioneer in the field of metabolic research, has developed a revolutionary weight-loss program that allows you to identify your “metabolic type” and create a diet that suits your individual nutritional needs.


In The Metabolic Typing Diet, Wolcott and acclaimed science writer Trish Fahey provide simple self-tests that you can use to discover your own metabolic type and determine what kind of diet will work best for you. It might be a low-fat, high carbohydrate diet filled with pasta and grains, or a high-fat, high-protein diet focused on meat and seafood, or anything in between. By detailing exactly which foods and food combinations are right for you, The Metabolic Typing Diet at last reveals the secret to shedding unwanted pounds and achieving optimum vitality with lasting results.


The Metabolic Typing Diet will enable you to:
Achieve and maintain your ideal weight
Eliminate sugar cravings
Enjoy sustained energy and endurance
Conquer indigestion, fatigue, and allergies
Bolster your immune system
Overcome anxiety, depression, and mood swings

Although I initially was impressed by the concept of the book and the first several chapters, there were several red flags and factual errors that undermined my confidence in the authors and the suggestions that they advocate. I am not disputing that there is some good advice in the book which can be beneficial to promoting good health, but I am concerned by several key points, some of which I will touch on briefly in this blog post. Note: I read the book with an open mind in its entirety before seeking out additional resources that share my concerns.

1. Red flag: The book lacks citations

Why did the authors choose not to use citations in their book? Aside from the occasional reference to a third-party resource, there were many claims and stated “facts” that were not supported by references directly in the text. Considering the nature of the book and the numerous scientific studies that surround the topics in the book, it would be desirable for any author on this subject to include footnotes or endnotes. This is due to either laziness, a lack of scientific support for the claims or the use of erroneous and fictitious information.

2. Red flag: Advocacy of the belief that aluminum foil is linked to the development of Alzheimer’s.

This book reinforced this fallacy which has been studied extensively since the concern about the link between aluminium foil and Alzheimer’s disease was first raised.

From an article on (link below):

“The overwhelming medical and scientific opinion is that the findings outlined above do not convincingly demonstrate a causal relationship between aluminium and Alzheimer’s disease, and that no useful medical or public health recommendations can be made − at least at present (Massey and Taylor 1989).”

(Please note: although this is just one source of information, it is based on at least 10 independent scientific journal articles that you can find listed below the article as references) To my knowledge, there have been no scientific studies directly linking aluminum foil to Alzheimer’s in the 23 years since the statement above was published.

3. Red flag: Advocacy that cold temperatures makes you more susceptible to colds.

This is one of the most studied myths in modern science. These factual errors make me concerned about how much of the content in the book is factual and how much is based on fiction. The last couple chapters would increase the anxiety of anyone who believed all of the information in the book was based on truth.

4. Red flag: Abundance of direct referrals.

I have never read a book that has had so many 1-800 numbers and websites for specific retailers of the products and services advocated by the authors. It’s one thing to make a recommendation for a type of product or service, but it’s another thing to name specific retailers. What kind of monetary incentives were established for the inclusion of these specific retailers? It’s hard to believe that none of the numerous retailers that were directly named (along with their website and 1-800 number) offered some kind of compensation to the authors for the endorsement. This raises concerns about the motives of the authors and the validity of the information.

5. Red Flag: Medical Concerns over the protein and fat-rich diet.

There are numerous health professionals and studies which refute the claims that high-protein, high-fat diets can be healthy for some individuals in the long run.

“The scientific literature is clear; there is no genetic type that has immunity from such a disease-causing, high saturated fat diet-style. All Americans, not just some, develop atherosclerosis on a diet so rich in animal products. Over ninety percent of Americans eventually develop atherosclerosis and hypertension from the low intake of unprocessed vegetables, fruits, beans, nuts and seeds. Our high intake of animal products AND processed foods and our low intake of unrefined plant food is the dietary pattern undeniably associated with these avoidable illnesses and a premature death from heart attacks or stroke.

Dr. Mercola’s position on saturated fat (high in cheese, butter and red meat) runs counter to thousands of medical research studies showing that saturated fat is the food factor most promoting [of] high cholesterol levels and heart disease. Though Dr. Mercola (like Atkins) denies the saturated fat–> high cholesterol–> heart disease link. Dr. Mercola’s topsy-turvy advice actually promotes the consumption of high saturated fat foods and makes ridiculous health claims…”

(Please note: I recognize that I should have spent more time to find more resources but this is the general consensus I’ve seen and I have yet to find any scientific data refuting this sentiment … please share it with me if you do find some).

6. The subjectivity of the test.

The questionnaire was highly subjective and it’s impossible for pre-existing beliefs and expectations not to influence the results. Our like and dislike for foods are heavily influenced by our perceptions and experiences and not necessarily our underlying biochemical needs. If one believes that eating a particular food will make you feel a certain way, it is likely that this individual will actually feel that way after consuming the food. Our subconscious mind is very capable of matching our moods to our expectations without conscious awareness (this is why scientific studies need to control for The Placebo effect).

Also, why are there numerous questions that only would result in the answer C (protein-type) but no questions that would result in only A or B to balance the number of potential A, B and C answers on the questionnaire?

7. Lack of scientific data supporting this +70 year-old theory and 12 year-old book.

There were a few success stories that were shared about the effectiveness of the author’s methods. In all, I would guess that there were less than 10 specific success stories provided (though they all sounded highly convincing). Why did the authors choose not to include more success stories and/or more data supporting the effectiveness of the diet? Presumably, Wolcott has helped significantly more people, which would represent a much higher sample size that he could reference. Why hasn’t Wolcott conducted/funded research proving the validity and effectiveness of his claims? I have yet to come across any scientific study that has supported this diet, though I would be very interested to read some if you come across any. I am aware that Dr. Oz and several other health professionals advocate this or a similar style of diet so maybe there are studies out there or maybe we’ll see a huge influx of studies validating this approach in the near future. If anyone knows of any, I’d be very interested in reading them so please leave a comment on this post.


I am not saying that the metabolic typing diet has no credibility. I believe that the core idea makes sense and that we should see metabolic differences based on the environment of evolutionary adaptiveness (EEA) of our ancestors. There are two questions that stand out in my mind which need to be answered:

1. Was the amount of time and the differences in the EEAs of our ancestors sufficient to create enough genetic variability to result in the significant degree of the contrasting dietary recommendations proposed by this diet?

2. If so, does adhering to the diet and recommendations in this book really result in all the physical and mental health benefits and the disease and cancer-free lives that the authors advocate?

Hopefully more research will investigate these claims and provide answers to my questions. Until then, I remain respectfully and healthily skeptical … though I would be happy to be relieved of my skepticism in the event that there are valid explanations for the red flags I’ve raised and there is scientifically validated data that supports this diet. If you have any comments, please leave them in the comment section below.

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