Skinny Fat Research

Since 2003, Fellow One Research has diligently researched (1) the phenomenon of skinny fat — even before the first official mention of skinny fat in 2006 (2). A key indicator of skinny fat is deficient muscle tissue, which starts with genetics (3, 4, 2). Yes, it is very possible to lose muscle via improper diet, exercise, and lifestyle, along with aging (sarcopenia), but lost muscle does not (5, 6, 3) turn into regular white/yellow body fat, or vice versa. This is not how human tissue works.

And this is readily evident in people like Christian Bale, who lost obvious muscle tissue due to poor diet, no less, yet he shows no signs of skinny fat (lack of genetic muscle):

The common gross assumption is that all human beings are born with the same general amount of muscle tissue relative to height and gender. But there is no science — zero — to support this false claim. Each human being is born (4, 3, 2) with their own unique amount of muscle tissue in relation to their specific genetics. Relative to their unique genetic muscle profile, particularly muscle fiber ratio — which directly affects how easy or how hard it is to add muscle mass and maintain existing muscle — they can reduce skinny fat (lack of genetic muscle), if they are experiencing it, by adding muscle mass to recomposition via proper resistance exercise like weightlifting.

However, adding muscle mass is not (7, 4, 3, 2) permanent. Any muscle mass added will have to be maintained forever, or you will gradually lose it and eventually return to your original genetic body composition.

Skinny Fat Research

Currently, there is no way to officially measure or diagnose skinny fat (lack of genetic muscle). No matter what misinformation and disinformation you come across on social media, in any AI tool, or the like. The current NIH definition of skinny fat — normal weight obesity (2) — claims that it is too much regular white/yellow body fat when within safe BMI. The problem is, that original 2016 NIH definition (2) directly contradicts (8, 9, 2) the approved and accepted standard BMI definition (2).

The BMI definition has not been officially changed through proper protocol since 1998 (2). It was not changed after the initial 2016 NIH normal weight obesity (skinny fat) definition was released, nor has it been since. Yet, countless doctors, scientists, and laypeople have casually changed the BMI definition on a whim and are pushing pseudoscience, all the while accusing anyone who disagrees with them of pseudoscience. This is not how science works. Yet, all too often, this is exactly how science inappropriately plays out.

Right now, there is only one scientific body type — the one all human beings are born in with all 600+ muscles developed. The Standard Body Type One (BT1), found in any scientifically approved human body anatomy book or reference (10). Regardless of the fact that there are countless human body shapes, thanks to genetics.

MRI Study – Skinny Fat Research

The only way to officially confirm a proper skinny fat definition and develop a diagnosis is through valid scientific research. The first step is establishing an accurate muscle tissue measurement, including a baseline average in which to compare each individual’s measurement. This is precisely what our MRI Study (11) is designed to do.

A major hurdle in such a research study is accurately screening study participants to ensure a valid and useful pool. Using the latest science, we have developed the Scientific Health Quizzes for this exact purpose. The Scientific Body Type Quiz accurately estimates body composition, particularly skinny fat. While the Scientific Metabolism Quiz accurately measures whether metabolism is slow, average, or fast, along with decreased, steady, or increased metabolic rate. The Scientific Diet, Exercise, and Lifestyle Quizzes round things out, helping to paint a whole picture of each participant.

These secure, private, anonymous (depending on what information you choose to give), and affordable Quizzes are available to the public as well. Accounts are free, and free options are available.

References

1. Fellow One Research: Body Type Science Research Data. https://fellowone.com/category/fellow-one-research/the-four-body-types/body-type-science/body-type-quiz/research-data/
2. Skinny Fat Science: What Is Skinny Fat?, July 26, 2024. https://skinnyfat.fellowone.com/skinny-fat-science/what-is-skinny-fat/
3. Skinny Fat Science: Is Muscle/Mass Genetic and How Does It Affect Skinny Fat?, November 20, 2024. https://skinnyfat.fellowone.com/skinny-fat-science/is-muscle-mass-genetic-and-how-does-it-affect-skinny-fat/
4. Skinny Fat Science: Is Skinny Fat Genetic?, November 27, 2024. https://skinnyfat.fellowone.com/skinny-fat-science/is-skinny-fat-genetic/
5. Skinny Fat Science: How To Fix Skinny Fat, July 27, 2024. https://skinnyfat.fellowone.com/skinny-fat-science/how-to-fix-skinny-fat/
6. Skinny Fat Science: Skinny Fat Body Composition – Before & After Weight Loss, July 2, 2025. https://skinnyfat.fellowone.com/skinny-fat-science/skinny-fat-body-composition-before-after-weight-loss/
7. Skinny Fat Science: Male, Skinny Fat But Muscular – Question, June 11, 2025. https://skinnyfat.fellowone.com/skinny-fat-science/male-skinny-fat-but-muscular-question/
8. Skinny Fat Science: Skinny Fat is a Lack of Genetic Muscle – Beyond Normal-Weight Obesity, August 13, 2025. https://skinnyfat.fellowone.com/skinny-fat-science/skinny-fat-is-a-lack-of-genetic-muscle-beyond-normal-weight-obesity/
9. Skinny Fat Science: Skinny Fat Is More Than Just Normal-Weight Obesity, April 2, 2025. https://skinnyfat.fellowone.com/skinny-fat-science/skinny-fat-is-more-than-just-normal-weight-obesity/
10. Britannica: human muscle system, Shane W. Cummings and Robin Huw Crompton (Fact-checked by the Editors of Encyclopaedia Britannica. https://www.britannica.com/science/human-muscle-system
11. Skinny Fat Science: Scientific Skinny Fat MRI Study – Proving What Skinny Fat Is, March 26, 2025. https://skinnyfat.fellowone.com/skinny-fat-science/scientific-skinny-fat-mri-study-proving-what-skinny-fat-is/