How Much Genetic Muscle Tissue Were You Born With or Without (Skinny Fat)?

Muscle directly affects metabolism (1). As a main glucose uptake tissue (2), muscle tissue burns calories, even when at rest. Some people genetically (3) have more muscle tissue, some less. How can we really know what “less” or “more” is when we do not have an average standard measurement to compare it to?

Typically, the more genetic muscle tissue you naturally have, the stronger your metabolism, no less. The less genetic muscle tissue (skinny fat)(4, 5, 3) you naturally have, the weaker your metabolism, the more sensitive you are to blood glucose spikes (from sugar and starch carbs), and the more prone you are to no less than insulin resistance, type-2 diabetes, being overweight, and obesity (1, 2, 3, 4, 5).

Yet, as of October 15, 2025, science/medicine has no way to measure total genetic muscle tissue. No standard average measurement to compare it to. And no way to measure added muscle mass via resistance/exercise. Not to mention, no way to track changes over time, including any potential muscle tissue lost during weight loss or aging (sarcopenia). There is no way to accurately know how much muscle tissue a person has before weight loss, let alone after — or ever.

How Much Genetic Muscle Tissue Were You Born With or Without (Skinny Fat)?

At this time, the easiest way to estimate total muscle tissue is by calculating lean body mass (LBM)(6, 7, 8). By definition, LBM is the weight of all body tissues (including water, brown fat, and beige fat) minus regular white/yellow body fat. The problem is, skinny fat (lack of genetic muscle, IE thin fat and cellulite) is NOT regular fat (9, 5). Thus, this must mean that skinny fat (thin fat, cellulite) is technically lean mass, right? Unlike regular white/yellow fat, which can be lost with proper diet, exercise, and lifestyle, skinny fat cannot be “lost” — it is permanent and can only be reduced (10).

A person who is near the low end of safe BMI at 18.5 — like Research Participant 1304 (11) at BMI 18.2 — but is experiencing skinny fat (lack of genetic muscle), has less genetic muscle tissue, and thus, less lean body mass, right?

RP 1304 is at BMI 18.2, which, by The Standard BMI definition (4, 5), means they have no excess regular white/yellow fat. In fact, they are underweight and have too little regular white/yellow fat. They cannot safely lose any more regular white/yellow fat. They are experiencing skinny fat (lack of genetic muscle, IE thin fat and cellulite). Thus, because skinny fat is NOT regular white/yellow fat, this means that skinny fat (thin fat, cellulite) is technically lean mass, as per the LBM definition, right?

Mitigating the Confusion

Yet, current inaccurate LBM estimates and/or DEXA/DXA (12, 13) scans, or the like, will inform RP 1304 that they still have too much regular white/yellow fat, and they need to lose more regular white/yellow fat via proper diet, exercise, and lifestyle to improve their LBM. When they do not have any more regular white/yellow fat to safely lose at BMI 18.2. Is it any wonder why the mental health crisis (especially eating disorders), no less, is getting worse?

Regardless, anyone experiencing skinny fat is, all too often, told that they still have too much regular white/yellow fat and need to lose more regular fat weight, no less. The fact is, muscle tissue is grossly assumed, whether relative to height (BMI), lean body mass calculations, or inferior DEXA scans or the like. There is zero science to support this very common gross assumption that all human beings are not born with the same general amount of genetic muscle tissue relative to height, or any other currently accepted inaccurate measure. Please comment below with science otherwise.

The Unwelcome Scientific Effects – Why Having No Muscle Tissue Measurement Standards Must Be Solved ASAP

To date, past scientific studies have functioned under that false gross assumption that all human beings are born with the same general amount of genetic muscle tissue relative to height. No study accurately knows how much genetic muscle tissue each person was born with or without (skinny fat), because no such standard measurement currently exists. Just as no study knows how much muscle mass was added via resistance/exercise, because no such measurement exists, at present.

Nevertheless, weight loss studies abound that continue to claim that muscle tissue was lost after weight loss. When those studies had/have no way to accurately measure how much muscle tissue each person had or did not have (skinny fat) before they lost the weight, let alone after. Not to mention, they had/have no standard average measurement to make an accurate comparison. What is the measurement for the average amount of genetic muscle tissue? Below average (skinny fat)? Above average?

Visit your licensed medical doctor and ask them how much total genetic muscle tissue you were born with or without (skinny fat). They cannot tell you because they do not know. Ask them how much muscle mass you have added via resistance/exercise, and they cannot tell you because they do not know. How can a doctor understand your metabolism and health, at least, when they do not know your muscle tissue measurements? How can they help you understand your unique body composition and shape? Or the best diet, exercise, and lifestyle for your specific genetic body? They cannot, not at this time.

How to Measure How Much Genetic Muscle Tissue Were You Born With or Without (Skinny Fat)?

Like any scientific standard measurement, science has to develop a standard measurement by bringing forward the proper scientific data. To do this, we have to be able to measure enough people’s total genetic muscle tissue as well as any added muscle mass. How is this achieved? The only technology capable of accurately measuring muscle tissue as required is an MRI (magnetic resonance imaging)(14) machine. This includes discerning the difference between existing genetic muscle (or lack of/skinny fat) and added muscle mass via resistance/exercise. As well as the difference between muscle, white/yellow fat, brown fat, beige fat, and skinny fat (thin fat, cellulite)(5), at least. 

Of course, this is no easy feat. It requires many proper MRI scans of real human beings who are carefully vetted. We need people who have all 600+ genetic muscles developed, as per the standard human body (AKA Standard Body Type One/BT1)(15). More to the point, we need enough Standard BT1 people relative to height to develop a general, accurate average(s). 

Once we have standard average muscle measurements, as needed, then we can do scans of people experiencing skinny fat (lack of genetic muscle), to whatever degree. We can compare the skinny fat person’s total muscle tissue (genetic and added) to the new standard average(s), to then validate and understand different degrees of skinny fat, no less. Along with the Scientific Body Type Quiz and other Scientific Health Quizzes (Metabolism, Diet, Exercise, Lifestyle) to accurately vet participants, our MRI Study (14) is the key to developing an accurate muscle measurement standard, so doctors can accurately diagnose skinny fat (lack of genetic muscle), at a minimum.

References

1. Skinny Fat Science: How Skinny Fat Affects Metabolism, August 7, 2024. https://skinnyfat.fellowone.com/skinny-fat-science/how-skinny-fat-affects-metabolism/
2. Skinny Fat Science: Skinny Fat & Insulin Resistance, June 4, 2025. https://skinnyfat.fellowone.com/skinny-fat-science/skinny-fat-insulin-resistance/
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: Skinny Fat is a Lack of Genetic Muscle – Beyond Normal-Weight Obesity, August 12, 2025. https://skinnyfat.fellowone.com/skinny-fat-science/skinny-fat-is-a-lack-of-genetic-muscle-beyond-normal-weight-obesity/
5. Skinny Fat Science: What Is Skinny Fat?, July 26, 2024. https://skinnyfat.fellowone.com/skinny-fat-science/what-is-skinny-fat/
6. Healthline: How Much Muscle Mass Should I Have, and How Do I Measure It?, May 7, 2025, Kirsten Nunez (Medically reviewed by Micky Lal, MA, CSCS,RYT). https://www.healthline.com/health/muscle-mass-percentage
7. MedicalNewsToday: How and why to calculate muscle mass percentage, September 2, 2024, Aaron Kandola (Medically reviewed by Megan Soliman, MD). https://www.medicalnewstoday.com/articles/muscle-mass-percentage
8. verywell fit: What Is Muscle Mass and How to Measure It, October 17, 2022, Shoshana Pritzker RD, CDN, CSSD, CISSN (Reviewed by Kristin McGee, CPT). https://www.verywellfit.com/ways-to-measure-muscle-growth-5272402
9. Skinny Fat Science: Are Regular Fat and Skinny Fat the Same Thing?, August 28, 2024. https://skinnyfat.fellowone.com/skinny-fat-science/are-regular-fat-and-skinny-fat-the-same-thing/
10. Skinny Fat Science: How To Fix Skinny Fat, July 27, 2024. https://skinnyfat.fellowone.com/skinny-fat-science/how-to-fix-skinny-fat/
11. Fellow One Research: Body Type Test (Quiz) Results 1304 – Body Type Two (BT2) Female (Woman), Millennial (Generation Y). https://www.fellowone.com/fellow-one-research/the-four-body-types/body-type-quiz/body-type-test-quiz-results-1304-body-type-two-bt2-female-woman-millennial-generation-y/
12. Skinny Fat Science: What Am I Skinny Fat?, December 25, 2025. https://skinnyfat.fellowone.com/skinny-fat-science/why-am-i-skinny-fat/
13. Skinny Fat Science: Skinny Fat People – What Does Skinny Fat Look Like?, June 1, 2025. https://skinnyfat.fellowone.com/skinny-fat-science/skinny-fat-people-what-does-skinny-fat-look-like/
14. 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/
15. 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