Low Muscle Mass, Skinny Fat, and How to Measure

A key symptom of skinny fat is low muscle mass. What exactly is low muscle? How is it measured? What threshold must be met to determine skinny fat? Venture out onto social media and you will find many different opinions on the subject. What does the science say?

Being able to measure muscle tissue, including mass, seems like it should be a common measurement. Like blood pressure, heart rate, cholesterol, A1C, etc., all of which offer scientifically/medically approved standard measurements so we can determine and know health, or lack of. None of those measurements are opinion. They are facts based on real science to help us understand and adjust diet, exercise, and lifestyle accordingly to be as healthy as possible. Those measurements have evolved over time and likely will continue to evolve as more scientific data rolls in.

Low Muscle Mass, Skinny Fat, and How to Measure

The next time you see your doctor, ask them how much muscle tissue you were naturally, genetically born with, and if your specific amount is average, above average, or below average. They cannot tell you because, currently, there is no way to officially, accurately measure muscle tissue/mass — be it genetic, added via resistance/exercise, or lost for whatever reason. Nor is there any accurate average to compare it to. Just as no official threshold exists to determine/diagnose skinny fat.

Why? Because human science, including skinny fat science, is so young, we have not developed such measurements, yet. To do so, we need the proper technology to do the necessary scientific research. Until recently, the technology did not exist, and remains difficult to access.

Many people claim that DEXA/DXA scans and InBody machines are capable of accurate muscle tissue measurements (“lean” body mass). They are not (1, 2, 3, 4, 5, 6, 7, 8, 9). Those technologies might be reasonable measures of body fat (but they cannot discern regular white/yellow fat from brown fat from beige fat), they cannot accurately measure muscle tissue. Even if they could, there is no standard muscle tissue average measurement to compare them to, to understand if a person has average, high, or low muscle tissue. And they most certainly cannot measure or diagnose skinny fat (lack of genetic muscle)(10, 11, 12). No matter what anyone says on social media or the like.

How To Accurately Measure Muscle Tissue and Skinny Fat

The only technology capable of accurately measuring total genetic muscle tissue, muscle mass added via resistance/exercise, and muscle tissue lost via poor diet, exercise, and lifestyle, is an MRI machine. Proper MRI scans can also accurately discern regular white/yellow fat from brown fat from beige fat. As well, they can accurately determine a lack of genetic muscle and any skinny fat (thin fat, cellulite (11, 12, 10)) present.

However, to date, no protocol exists, nor any approved way to accurately measure muscle tissue in any standard capacity. This is largely due to the fact that MRI scans are very expensive and access is very limited. Although prices are coming down and access is beginning to open up more. We need proper approved protocol and standard measures so that the average person can better understand their unique genetic body composition, shape, and metabolism to make the healthiest diet, exercise, and lifestyle choices for them.

Our MRI Study (12, 10, 11) is working on doing the necessary scientific research to develop the approved protocol and standard muscle measures, including the ability to diagnose skinny fat. Using the latest science, we have already developed the Scientific Health Quizzes, including the Scientific Body Type Quiz, Scientific Metabolism Quiz, Scientific Diet Quiz, and Scientific Exercise Quiz. Each Quiz helps you understand your unique genetic body composition, particularly skinny fat, and metabolism to understand and choose the best diet, exercise, and lifestyle for you. Accounts are free, private, secure, and anonymous. Free options are available.

References

1. Nature, Scientific Reports: Changes in DXA-derived lean mass and MRI-derived cross-sectional area of the thigh are modestly associated, July 11, 2019, Dallin Tavoian, Kwasi Ampomah, Shinichi Amano, Timothy D. Law, and Brian C. Clark. https://www.nature.com/articles/s41598-019-46428-w
2. NIH, National Library of Medicine: Reliability and Agreement of Various InBody Body Composition Analyzers as Compared to Dual-Energy X-Ray Absorptiometry in Healthy Men and Women, July-September 2020. Cherilyn N McLester, Brett S Nickerson, Brian M Kliszczewicz, and John R McLester. https://pubmed.ncbi.nlm.nih.gov/30472111/
3. Cleveland Clinic: DXA Scan (Bone Density Test), May 28, 2024. https://my.clevelandclinic.org/health/diagnostics/10683-dexa-dxa-scan-bone-density-test
4. Wikipedia: Dual-energy X-ray absorptiometry, https://en.wikipedia.org/wiki/Dual-energy_X-ray_absorptiometry
5. NIH, National Library of Medicine: Dual-Energy X-Ray Absorptiometry: Research Issues and Equipment, 1997, Wendy M. Kohrt. https://www.ncbi.nlm.nih.gov/books/NBK233779/
6. Journal of Applied Physiology: Percent body fat via DEXA: comparison with a four-compartment model, February 1, 2003, Grant E. van der Ploeg, Robert T. Withers, and Joe Laforgia. https://journals.physiology.org/doi/full/10.1152/japplphysiol.00436.2002
7. UC Davis Health, Sports Medicine: DXA body composition analysis, https://health.ucdavis.edu/sports-medicine/resources/dxa-info
8. MedlinePlus: Bone Density Scan. https://medlineplus.gov/lab-tests/bone-density-scan/
9. METS Performance: Is An InBody Scan Accurate?, November 21, 2024, Luke McIlroy. https://metsperformance.com/blog/is-an-inbody-scan-accurate
10. 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/
11. Skinny Fat Science: What Is Skinny Fat?, July 26, 2024. https://skinnyfat.fellowone.com/skinny-fat-science/what-is-skinny-fat/
12. 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/