Is Low Muscle Genetic?

Is low muscle genetic? Most people don’t realize that, at present, there is no way to measure (1, 2) how much genetic muscle tissue each human being is born with, or without (skinny fat). Nor how much they have throughout their life. There is no way to measure added muscle mass from resistance/exercise. Just as there is no way to measure how much muscle tissue is lost due to diet, exercise, lifestyle, or aging (sarcopenia). And, even if any of those measurements did exist, there is no average to compare them to.

Muscle is genetic (3). No different than skin color, eye color, hair color, height, hand size, foot size, genital size, breast size, facial features, etc. None of those things can be willfully, naturally, and permanently changed. Genetics. Body composition is no different. Some people are born with more muscle, some less.

It is true that resistance training, especially weightlifting, can add muscle mass to increase total muscle and recomposition your body. But, added muscle mass is not permanent (epigenetics are not permanent)(4, 3). If/when you stop doing the exercise(s) that built the added muscle, you will gradually lose it and eventually return to your original genetic body composition and muscle tissue levels. Not to mention how that added muscle mass is built — is it done symmetrically (or asymmetrically like Homer Simpson)?

Genetic Low Muscle (Skinny Fat)

Yes, low muscle — skinny fat — is genetic (5, 3). Where genetic muscle should be but is not, something has to exist in its place. That something is thin fat and/or cellulite tissue (6) — our MRI Study (7) is working on proving this once and for all. Another question our study will answer is, can you have low genetic muscle tissue and not have skinny fat?

If you have spent any time out on social media, you likely will have heard that genetics are just an excuse. They are not. Just as you likely have heard the gross insinuation that all human beings are born with the same general amount of muscle tissue relative to height and gender — when there is zero science to support this false claim. Every human body is a unique genetic creation. The vast majority of influencers who are athletically fit and ripped are genetically blessed. Like nearly all professional athletes.

Yet, most — if not all — of those influencers will claim (all too often by shaming and bullying) that genetics has nothing to do with it — it’s just hard work. Stop being so lazy and work harder. Easy to say when you’re genetically blessed with all 600+ muscles fully developed — AKA a Standard Body Type One (BT1)(8). This is one of the many reasons why our MRI Study (7) is so vital to bringing forward the real science; to ground the facts and stop the widespread misinformation, disinformation, and outright lies. If you are born with less genetic muscle, yet being told you have the same genetic muscle as everyone with your general metrics, it leads to serious self-confidence and other mental health issues, along with poor diet, exercise, and lifestyle choices, which negatively effects metabolism and body composition.

Solutions – Scientific Health Quizzes

We have spent the last 6 years developing the Scientific Health Quizzes, scouring the scientific literature and testing via nearly 500 research participants (9). The Scientific Body Type Quiz accurately estimates body composition, particularly skinny fat. The Scientific Metabolism Quiz accurately calculates your unique metrics to determine whether your metabolism is slow, slow average, average, average fast, or fast, and if your metabolic rate is decreased, steady, or increased.

Moreover, the Scientific Diet, Exercise, and Lifestyle Quizzes round things out to paint a complete picture. All of which helps you better understand your specific health. Accounts are free, private, secure, and anonymous (depending on what info you choose to give). You can track your progress over time by taking as many Quizzes as you want. Free options are available.

References

1. Skinny Fat Science: Low Muscle Mass, Skinny Fat, and How to Measure, December 10, 2025. https://skinnyfat.fellowone.com/skinny-fat-science/low-muscle-mass-skinny-fat-and-how-to-measure/
2. Skinny Fat Science: Skinny Fat Body Fat Percentage, February 25, 2026. https://skinnyfat.fellowone.com/skinny-fat-science/skinny-fat-body-fat-percentage/
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: How To Fix Skinny Fat, July 27, 2024. https://skinnyfat.fellowone.com/skinny-fat-science/how-to-fix-skinny-fat/
5. Skinny Fat Science: Is Skinny Fat Genetic?, November 27, 2024. https://skinnyfat.fellowone.com/skinny-fat-science/is-skinny-fat-genetic/
6. Skinny Fat Science: What Is Skinny Fat?, July 26, 2024. https://skinnyfat.fellowone.com/skinny-fat-science/what-is-skinny-fat/
7. Skinny Fat Science: Scientific Skinny Fat MRI Study – Proving What Skinny Fat Is, May 26, 2025. https://skinnyfat.fellowone.com/skinny-fat-science/scientific-skinny-fat-mri-study-proving-what-skinny-fat-is/
8. 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
9. 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/