Skinny Fat Is More Than Just Normal-Weight Obesity

First mentioned in the official literature in 2006 (1), the first known NIH definition for skinny fat was normal-weight obesity in 2016 (2).

“Normal-weight obesity syndrome is characterized by excess body fat in individuals with adequate body mass index (18.5-24.9 kg/m(2))”

At least one problem with that initial definition is that it directly contradicts the Standard BMI definition (1). The BMI serves one single purpose. Using height and weight it estimates body fat to assess health risks that can occur with excess body fat or too little body fat. Once you are within safe BMI — 18.5 to 24.99 — you no longer have any excess body fat (regular white/yellow fat/common adipose tissue), by BMI definition.

So, how can the definition of normal-weight obesity contradict the BMI? It cannot. You cannot ignore an accepted standard to create a new definition.

Hypothesis Overview – Skinny Fat Is More Than Just Normal-Weight Obesity

Our skinny fat science theory includes the main hypothesis that is grounded in the fundamental concept that skinny fat is unique genetic tissue — thin fat and cellulite — that exists where genetic default muscle tissue should be but is not. Every human being is born with all the natural genetic muscle fibers (3) they will ever have at or around birth. Some people are born with more muscle fibers and some less.

Muscle fiber ratio (3) also matters, as how optimal each person’s muscle fiber ratio is determines how easy or how hard it is for them to add muscle mass and maintain it. As well, muscle directly affects (3) metabolism, strength, power, reaction time, speed, balance, coordination, agility, flexibility, endurance, and overall athleticism and movement, no less.

It is an undisputed scientific/medical fact (4, 5, 6, 7) that muscle tissue cannot turn into any kind of fat tissue. Just as no kind of fat tissue can turn into muscle tissue. This is not how human tissue works. Thus, the common claim that lost muscle tissue becomes any kind of fat/skinny fat is false. If that were true — that lost muscle tissue becomes skinny fat — then it would apply equally to 100% all human beings. But it does not apply to genetically blessed Christian Bale when he lost obvious muscle tissue while losing weight down to roughly BMI 16.5, yet no skinny fat.

What Is A Normal/Average Human Body?

According to mainstream science/medicine, every human being is born is an “average/normal” standard human body (AKA Standard Body Type One/BT1) as per any approved human body anatomy resource (8) with all 600+ muscles genetically developed (unless they are diagnosed with some abnormality, but they are still a Standard BT1 just with a specific diagnosis).

The only reason you do not look like a Standard Body Type One (BT1) is you are eating too many calories above Standard BMR taking you outside of safe Standard BMI (18.5 to 24.99) due to excess regular white/yellow body fat (common adipose tissue)(1). Stop overeating (too many calories), lose the excess regular fat weight, and voila, you are once again a Standard BT1.

However, our research (18, 19) shows this is simply not true; all human beings are not born in s Standard BT1. Some people are born with more muscle tissue, and some with less. Those born with less are experiencing some degree of skinny fat tissue. We can prove this with proper MRI scans. 

Hypothesis

If a person is experiencing genetically underdeveloped default muscle tissue/fibers, to whatever degree, then some kind of genetic tissue must exist in its place – that tissue is skinny fat tissue, IE thin fat tissue and/or cellulite tissue (we can prove this with our MRI Study).

For example, see this pro trainer’s lower back and love handles:

They have no visceral/belly fat, no excess body fat (white/yellow fat) at a safe BMI of 22.7, and no low muscle mass — all supposed signs of skinny fat. Yet obvious “weird fat” tissue on their lower back and love handles where genetically they should have default genetic muscle tissue but do not.

No process exists in the human body that would cause that person’s muscle tissue on their love handles and lower back to turn into any kind of fat tissue. They are within safe BMI at 22.7, so that “weird fat” tissue is not regular white/yellow body fat. We know that “weird fat” tissue is not muscle tissue and it is not regular white/yellow body fat tissue. So, what kind of tissue is it?

Brown fat tissue or beige fat tissue? Very unlikely, as both of those tissues increase metabolic rate and encourage the burning of white/yellow fat to help mitigate (13, 14, 15, 16, 17) being overweight or obese, not cause it in any form. Keep in mind that Research Participant 1000 (10) and Research Participant 1088 (11) do not have that “weird fat” tissue. They have obvious muscle tissue, as per the Standard BT1 with all 600+ muscles genetically developed. That “weird fat” tissue is thin fat skinny fat tissue (1). We can prove this with our MRI Study.

A Classic Example of Normal-Weight Obesity

Research Participant 1170 (12) is at a safe BMI of 24.6 while clearly experiencing normal-weight obesity; IE they have “weird fat” tissue — what appears to be too much/excess body fat (white/yellow fat) — all over their body where they should genetically have muscle tissue, as per the Standard Body Type One (BT1):

They safely lost more regular fat weight down to a safe BMI of 21.3, yet the “weird fat” and normal weight obesity remain. There are no obvious signs of the genetic default muscle tissue they are supposed to have, as per the Standard BT1. They clearly stated (12) that they have never had the Standard BT1 muscle tissue. 

Because they are within safe BMI, we know they are not experiencing too much/excess white/yellow body fat. It is not muscle tissue. It is very unlikely that it is brown or beige fat tissue, as those tissues increase metabolic rate and help burn fat tissue, especially white/yellow fat tissue, to mitigate (17, 13, 14, 15, 16) being overweight or obese.

So, what is the “weird fat” tissue all over their body where they should have genetic default muscle tissue, but do not? It is thin fat tissue and cellulite tissue; both types of skinny fat. We can prove this with our MRI Study.

What if Research Participant 1170 were to reduce their regular white/yellow body fat to an underweight BMI of 18.49 or less?

Would the thin fat and cellulite go away? No, it would not — there is no FDA-approved way to get rid of cellulite or thin fat, you can only reduce it. And like this person (20) who lost weight down to a BMI of 8, any eating disorder person eventually learns and can tell you that you cannot starve away skinny fat. You can technically lose 100% of your regular white/yellow fat, yet your skinny fat (thin fat and/or cellulite) will remain down to any BMI. But they would no longer be experiencing normal-weight obesity. 

What if Research Participant 1170 were to increase their regular white/yellow body fat to an overweight BMI of 25+ or 30+ obese?

Would the thin fat and cellulite go away? No, it would not. Again, at this time, no FDA-approved way exists to get rid of cellulite or thin fat, you can only reduce it. Their skinny fat would remain up to any BMI. But they would no longer be normal-weight obese. Yet, they are still experiencing skinny fat (thin fat, cellulite). We can only prove those things with a proper MRI Study.

Skinny fat is so much more complex than the initial 2016 NIH definition (2). Science is ever-evolving and things become more clear as more data, evidence, and facts roll in. Which our MRI Study can provide and achieve.

How To Know If You Are Skinny Fat – Developing An Official Skinny Fat Diagnosis

References

1. Skinny Fat Science: What Is Skinny Fat?, July 26, 2024. https://skinnyfat.fellowone.com/skinny-fat-science/what-is-skinny-fat/
2. NIH, National Library of Medicine: Normal-weight obesity syndrome: diagnosis, prevalence, and clinical implications, September 2016 (Epub Jul 29, 2016), Lana P Franco, Carla C Morais, Cristiane Cominetti. https://pubmed.ncbi.nlm.nih.gov/27473199/
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. NIH, National Library of Medicine: Muscle-to-fat interaction: a two-way street?, January 1, 2010, Bente K Pedersen. https://pmc.ncbi.nlm.nih.gov/articles/PMC2821541/
5. Healthline: Does Fat Turn into Muscle? What to Know, March 2, 2021, Katey Davidson, MScFN, RD, CPT (Medically reviewed by Jake Tipane, CPT). https://www.healthline.com/nutrition/does-fat-turn-into-muscle
6. The New York Times: The Claim: Muscle Turns to Fat When You Stop Working Out, July 26, 2006, Anahad O’Connor. https://www.nytimes.com/2005/07/26/health/nutrition/the-claim-muscle-turns-to-fat-when-you-stop-working-out.html
7. Skinny Fat Science: How To Fix Skinny Fat, July 27, 2024. https://skinnyfat.fellowone.com/skinny-fat-science/how-to-fix-skinny-fat/
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 Test (Quiz) Results 1170 – Body Type Three (BT3) Female (Woman), Generation Z, February 2022. https://www.fellowone.com/fellow-one-research/the-four-body-types/body-type-quiz/body-type-test-quiz-results-1170-body-type-three-bt3-female-woman-generation-z/
10. Fellow One Research: Body Type Test (Quiz) Results 1000 – Body Type One (BT1) Male (Man), Millennial (Generation Y). https://www.fellowone.com/fellow-one-research/the-four-body-types/body-type-quiz/body-type-test-quiz-results-1000-body-type-one-bt1-male-man-millennial-generation-y/
11. Fellow One Research: Body Type Test (Quiz) Results 1088 – Body Type One (BT1) Male (Man), Millennial (Generation Y). https://www.fellowone.com/fellow-one-research/the-four-body-types/body-type-quiz/body-type-test-quiz-results-1088-body-type-one-bt1-male-man-millennial-generation-y/
12. Fellow One Research: Body Type Test (Quiz) Results 1170 – Body Type Three (BT3) Female (Woman), Generation Z, February 2022. https://www.fellowone.com/fellow-one-research/the-four-body-types/body-type-quiz/body-type-test-quiz-results-1170-body-type-three-bt3-female-woman-generation-z/
13. Cleveland Clinic: Brown Fat, September 07, 2022. https://my.clevelandclinic.org/health/body/24015-brown-fat
14. NIH, National Institutes of Health: How brown fat improves metabolism, September 10, 2019. https://www.nih.gov/news-events/nih-research-matters/how-brown-fat-improves-metabolism
15. Harvard Medical School, News & Research: How Brown Fat Burns Energy, July 3, 2014, Bonnie Prescott. https://hms.harvard.edu/news/how-brown-fat-burns-energy
16. NIH, National Library of Medicine: Brown and Beige Adipose Tissue, September 2016, Anny Mulya and John P Kirwan. https://pmc.ncbi.nlm.nih.gov/articles/PMC5206678/
17. Nature, science reports: Iron chelation increases beige fat differentiation and metabolic activity, preventing and treating obesity, January 14, 2022, Mojgan Nazari, Kenneth W. Ho, Natasha Langley, Kuan M. Cha, Raymond Kodsi, Mawson Wang, D. Ross Laybutt, Kim Cheng, Rebecca A. Stokes, Michael M. Swarbrick, and Jenny E. Gunton. https://www.nature.com/articles/s41598-022-04809-8
18. Fellow One Research: Body Type Science Research Data. https://www.fellowone.com/category/fellow-one-research/the-four-body-types/body-type-science/body-type-quiz/research-data/
19. Fellow One Research: Skinny Fat Science. https://skinnyfat.fellowone.com/skinny-fat-science/
20. DailyMail: From anorexic to body builder: Woman who was on the brink of death after dropping to FOUR STONE becomes a champion weight lifter in just 18 MONTHS, April 4, 2017, Martha Cliff. https://www.dailymail.co.uk/femail/article-4378340/Recovering-anorexic-wins-bodybuilding-title.html