Skinny fat, or skinny fat body type, refers to being a moderate weight or underweight but having a higher proportion of body fat than is healthy.

Skinny fat also means having lower than ideal lean body mass, which includes everything in the body except the fat, such as the organs, bones, muscles, blood, and skin.

A person’s lifestyle and genetics can affect their risk of developing skinny fat. Making dietary and lifestyle modifications can help to counteract the condition.

This article examines what skinny fat means, who is at risk, and what they can do about it.

Healthcare professionals do not use the term “skinny fat.” They typically refer to this condition as “normal weight obesity” or “thin outside, fat inside (TOFI).”

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People often associate obesity with metabolic health problems, such as heart disease and type 2 diabetes. However, some people with obesity are in good metabolic health.

Conversely, some people who appear to have lean bodies are at risk of cardiometabolic diseases, such as heart attack, stroke, and diabetes. Healthcare professionals term this group of people metabolically obese, normal weight (MONW) — also known as skinny fat.

Studies show a significant rise in cases of type 2 diabetes over the past 30 years, and researchers predict that the number will continue to rise. This increase in overweight and obesity has paralleled changing trends in modern lifestyle habits.

Researchers have also linked metabolic syndrome to abdominal obesity specifically. Having extra fat around the midsection does not necessarily mean that a person will have a high body mass index (BMI) or waist circumference.

Read about the limitations of BMI.

One study explained that people with skinny fat may show signs such as:

  • excess fat tissue around the internal organs
  • fat deposits in tissue that normally does not contain much fat
  • fat tissue inflammation
  • altered inflammatory and metabolic profiles
  • reduced skeletal muscle mass
  • low cardiorespiratory fitness, which is the ability to use oxygen to move or exercise

Researchers have also observed people with skinny fat may carry more body fat than people who are metabolically healthy and lean.

A study from 2019 reported that calculating a person’s waist-to-height ratio is the easiest way to measure this central obesity. It also produces the most valid results.

One review from 2022 reported that skinny fat results from both genetic factors and environmental factors, including:

  • lack of physical activity
  • unhealthy diet
  • smoking
  • alcohol consumption

Researchers studying South Asian populations also highlighted the potential role of variants in certain genes in predisposing individuals to a “thin-fat” body type.

A 2022 review listed changing lifestyles, lack of exercise, and processed food consumption as reasons for the rise in obesity in general. The authors added that the number of people with “normal weight obesity” might also be increasing.

However, the lower BMI of people with “normal weight obesity” makes the condition less visible and more difficult to diagnose. This makes preventing skinny fat harder, as people may not know they have it until they receive a diagnosis of another condition, such as diabetes or insulin resistance.

Eating unhealthy foods can affect a person’s risk of developing skinny fat.

For instance, one 2023 cross-sectional study found that the group of participants with skinny fat ate ultra-processed food (UPF) and drank beverages with added sugar more regularly than the group who did not have skinny fat.

Researchers have described UPF as food that is prepared in an industrial setting. It usually contains at least five of the following ingredients:

  • sugar
  • oils
  • fats
  • salt
  • antioxidants
  • stabilizers
  • preservatives

Examples of UPF include:

  • ice cream
  • chocolate and candy
  • mass-produced packaged bread
  • margarine and fat spread
  • cookies, pastries, and cakes
  • chicken nuggets and hot dogs
  • preprepared pies, pasta, and pizza

Additionally, the International Society of Sports Nutrition (ISSN) has stated that a person needs to be taking in fewer calories than they are using if they want to focus their diet on fat loss.

The higher the amount of body fat they have to begin with, the stricter they can be with reducing calories.

The ISSN also says that losing weight more slowly better preserves lean body mass in leaner people.

It is best for individuals to discuss major changes in diet with a healthcare professional to ensure they are eating a balanced diet and losing weight safely.

Can eating better improve body composition?

Making dietary adjustments, including limiting or avoiding UPF, may help a person improve their body composition.

One study suggested that people could help prevent and treat the syndrome known as TOFI by:

  • increasing physical activity
  • improving diet
  • using the diabetes medication metformin

People should only use medications that are recommended and prescribed to them by a healthcare professional.

Smoking and alcohol consumption are potential causes of skinny fat. Stopping smoking and avoiding alcohol may help reduce skinny fat.

Additionally, a lack of physical activity may increase the risk of developing skinny fat. Similarly, regularly exercising may help reduce skinny fat.

No specific treatments exist for people with a MONW body type, according to a study from 2016. Instead, they tend to receive the same treatment as people who have metabolically unhealthy obesity.

This involves lifestyle modifications along with appropriate management for any underlying health conditions.

Some people can have a normal BMI but a disproportionately high amount of body fat. This is known as skinny fat, and it can increase the risk of conditions such as diabetes, heart disease, and stroke.

Some people have genetic variants that place them at higher risk of becoming skinny fat. Lifestyle factors such as a lack of exercise, an unhealthy diet, smoking, and alcohol consumption can also play a role.

Individuals may be able to reduce skinny fat or prevent it by improving eating habits, getting regular exercise, and following treatment instructions for underlying health conditions.