Skinny Fat Female with Low BMI – Question

My Skinny Fat Question. Hello, I am an 18-year-old female and even though my BMI is low at 18.5, I am experiencing skinny fat. I thought that I would have gotten rid of it by now. I spend a lot of time on social media and everyone keeps telling me that I need to lose more fat weight to get rid of my skinny fat.

This does not make sense to me. First, where is my muscle? I was very careful to lose fat weight safely to avoid muscle loss. My diet is healthy, including a 500-calorie deficit, and I make sure to get enough protein. I avoid carbs, at least sugar carbs, and pay attention to my fiber and good fats. For exercise I jog to get my cardio and work on adding muscle mass with calisthenics; I don’t have access to weights.

I am already at the very low end of the healthy BMI range. If I lose any more fat weight I will be underweight. I don’t want to be unhealthy, but I do want to get rid of my skinny fat. What do I need to do? PS: Sorry, I am not comfortable sending images.

Skinny Fat Female with Low BMI

You are correct, losing more regular white/yellow body fat (1) to a lower underweight BMI (18.49 or less) is not healthy and will not help you fix your skinny fat. For instance, see how this emaciated person failed to starve away their skinny fat at BMI 8 (2):

They have minimal muscle tissue (skinny fat) on their stomach and love handles, no less, thanks to their unique genetics. They were finally successful at reducing their skinny fat by adding muscle mass in recovery.

Whereas, see how emaciated genetically blessed Christian Bale lost a lot of weight including obvious muscle tissue:

Yet, the muscle definition including 6-pack abs and muscle on his love handles is clear, no less, while emaciated! And no skinny fat. Genetics.

Skinny Fat is Genetic and Exists Where Genetic Default Muscle Tissue Should Be, But is Not

Muscle is genetic (3, 4), as is muscle fiber ratio. Females typically have less genetic muscle tissue and more regular fat tissue (5) compared to males. Skinny fat (6, 7, 9) exists anywhere genetic default muscle tissue should be, but is not.

For example, here is a classic case of skinny fat (normal-weight obesity):

See how Research Participant 1170 (8) is within safe BMI at 24.6 yet experiencing obvious normal weight obesity (skinny fat) — they have “weird fat” widespread across their body where they should have genetic default muscle tissue but do not:

See how they lost regular white/yellow body fat (common adipose tissue) down to a BMI of 21.3, yet the “weird fat” remains in all the same places where they should have genetic muscle tissue but do not…that weird fat is skinny fat — thin fat and cellulite:

If they were to decrease their regular white/yellow body fat to an underweight BMI of 18.49 or less, would the skinny fat go away? No.

They would no longer be normal-weight obese, but they would still be experiencing the thin fat and cellulite tissue that is widespread across their body where they should have genetic muscle tissue. It does not magically go away at a BMI of 18.49 or less.

If they were to increase their regular white/yellow body fat to an overweight BMI of 25+ or 30+ obese, would the skinny fat go away? No.

They would no longer be normal-weight obese, but they would still be experiencing the thin fat and cellulite tissue that is widespread across their body where they should have genetic muscle tissue. It does not magically go away at a BMI of 25 or a BMI of 30 or beyond.

RP 1170 was born with underdeveloped genetic muscle tissue and where that muscle tissue should be they are experiencing skinny fat tissue; thin fat and cellulite (our MRI Study (9) is working on proving this once and for all).

Low BMI – Skinny Fat Female

Like RP 1170, your skinny fat (lack of genetic muscle tissue) is genetic — you have had it since birth. The next time you visit your doctor, ask them how much muscle tissue you were born with (or without) — the actual measurement(s). They most likely do not know, like 99%+ of human beings. You, like your doctor and the vast majority of people globally, ASSUME that you were born with all 600+ muscles developed, as per the standard human body (10):

But, the fact is, many human beings are born with genetically underdeveloped muscle(s) (skinny fat). The latest scientific data indicates that likely roughly 2/3rds (11) of the population are genetically experiencing some degree of skinny fat.

Calorie deficits can be tricky and tend towards muscle tissue loss. A 500-calorie deficit is the current norm. However, all too often it leads to muscle tissue loss (12, 13, 15) and slowed metabolism (14), no less, no matter how diligent you are with your diet. Because each human body is genetic, and how your genetics behave is different than anyone else in existence. Lost muscle tissue can make any existing skinny fat worse. The more exercise you do and the lower your daily calories relative to BMR/TDEE (Total Daily Energy Expenditure), the more probable it is that you lose muscle mass and make any existing skinny fat worse.

Low Carb Diet, Exercise, & Lifestyle

For many people, a proper low-carb diet (15) is a better choice as no calorie deficit is required which helps minimize muscle loss. For acute weight loss, eat 37 grams (16) of fiber-focused carbs. Avoid all sugar and starch carbs. If your body does not respond well to a proper low-carb diet, then you may have to incorporate a safe calorie deficit. Start at 300 calories, carefully making sure you get ALL your daily protein, fat, fiber, vitamin, and mineral nutrients.

Your cardio and resistance exercise routines will help burn more calories to speed things up: 150 minutes to 300 minutes of moderate-intensity exercise or 75 minutes to 150 minutes of vigorous-intensity — or a combination, with no more than 600 total minutes per week (17). Make sure you adjust your BMR/TDEE (Total Daily Energy Expenditure) protein and fat calories accordingly, to avoid muscle tissue loss.

Once you lose the fat weight desired, increase your carbs to between 50 grams and 150 or so grams of fiber-focused carbs — how much for you depends on your unique genetics and how much skinny fat you are experiencing. The more skinny fat you are experiencing the more sensitive (18, 13) you likely are to sugar and starch carbs, blood sugar/glucose spikes, insulin resistance, type-2 diabetes, and being overweight or obese.  Avoid sugar and starch carbs. Of course, lifestyle (19), particularly proper sleep, also matters.

Adding Muscle Mass is the Best Way to Reduce Skinny Fat

Fixing your skinny fat starts with understanding your unique genetic body composition and metabolism. Where are you experiencing skinny fat and how much? We developed the Scientific Health Quizzes including the Scientific Body Type Quiz and Scientific Metabolism Quiz to help. Once you know where you are experiencing skinny fat on your body, then you can focus on proper resistance exercises (20, 21, 14) to build the necessary muscle mass to reduce it as much as possible.

Keep in mind, your unique genetic muscle fiber ratio matters, as it determines how easy or how hard it is for you to add muscle mass and maintain it. As well, any muscle mass you add you will have to maintain forever. Like losing regular fat, adding muscle mass is not permanent.

References

1. 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/
2. 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, Marth Cliff. https://www.dailymail.co.uk/femail/article-4378340/Recovering-anorexic-wins-bodybuilding-title.html
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: Skinny Fat Genetics, Race DNA, and Muscle Tissue, June 18, 2025. https://skinnyfat.fellowone.com/skinny-fat-science/skinny-fat-genetics-race-dna-and-muscle-tissue/
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: 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/
8. 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/
9. 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/
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. 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/
12. Scientific American: Why You Don’t Just Lose Fat When You’re on a Diet, July 13, 2023, Adam Collins & The Conversation US. https://www.scientificamerican.com/article/weight-loss-why-you-dont-just-lose-fat-when-youre-on-a-diet/
13. Skinny Fat Science: Calorie Deficit for Skinny Fat, January 22, 2025. https://skinnyfat.fellowone.com/skinny-fat-science/calorie-deficit-for-skinny-fat/
14. Skinny Fat Science: How Skinny Fat Affects Metabolism, August 7, 2024. https://skinnyfat.fellowone.com/skinny-fat-science/how-skinny-fat-affects-metabolism/
15. Skinny Fat Science: The Best Skinny Fat Diet, According to Science, July 29, 2024. https://skinnyfat.fellowone.com/skinny-fat-science/the-best-skinny-fat-diet-according-to-science/
16. Today Show: Can’t lose weight by eating less? Why low-carb diets may be the solution, June 06, 2022, Morgan Radford, Lauren Dunn and A. Pawlowski. https://www.today.com/health/diet-fitness/weight-loss-low-carb-diets-rcna31724
17. Skinny Fat Science: The Best Skinny Fat Exercise, According to Science, August 2, 2014. https://skinnyfat.fellowone.com/skinny-fat-science/the-best-skinny-fat-exercise-according-to-science/
18. Skinny Fat Science: Skinny Fat & Insulin Resistance, June 4, 2025. https://skinnyfat.fellowone.com/skinny-fat-science/skinny-fat-insulin-resistance/
19. Skinny Fat Science: The Best Skinny Fat Lifestyle, According to Science, August 14, 2024. https://skinnyfat.fellowone.com/skinny-fat-science/the-best-skinny-fat-lifestyle-according-to-science/
20. Skinny Fat Science: Resistance Training for Skinny Fat – Weight Lifting, 40 Optimal Exercises (with Images), May 7, 2025. https://skinnyfat.fellowone.com/skinny-fat-science/resistance-training-for-skinny-fat-weight-lifting-40-optimal-exercises-with-images/
21. Skinny Fat Science: Best Skinny Fat Resistance Exercises, September 4, 20254. https://skinnyfat.fellowone.com/skinny-fat-science/best-skinny-fat-resistance-exercises/