Belly Fat Isn't All the Same: Why Visceral Fat Can Be a Health Concern
Many people judge body fat by what they can see in the mirror, but the most important fat for health is often hidden deep inside the abdomen.
Visceral fat, sometimes called visceral adipose tissue, surrounds organs such as the liver, pancreas and intestines. Unlike the fat you can pinch under the skin, visceral fat is biologically active and strongly linked with diabetes, heart disease and other metabolic conditions.
'Visceral adipose tissue is the fat that is stored deep in the abdomen and surrounds the organs,' explained Dr Jumana Al-Deek, DO, MS.
'It is more metabolically active, more insulin-resistant, more pro-inflammatory and produces more harmful free fatty acids than subcutaneous fat.'
Understanding the difference between these two types of fat is important because someone can appear relatively slim yet still carry an unhealthy amount of visceral fat.
What Is the Difference Between Visceral Fat and Subcutaneous Fat?
Subcutaneous fat sits directly beneath the skin. It is the fat found on the arms, legs, hips and around the stomach that can be seen and felt.
Visceral fat, by contrast, lies deeper within the abdomen and wraps around internal organs.
Subcutaneous fat makes up most of total body fat, while visceral fat usually represents a smaller proportion. However, its location and behaviour make it more concerning.
Dr Al-Deek said visceral fat has a richer blood supply and acts almost like an endocrine organ, releasing inflammatory substances and fatty acids into the bloodstream.
This means visceral fat can affect organs throughout the body rather than simply serving as energy storage.
Why Is Visceral Fat More Harmful?
Researchers believe visceral fat is harmful for several reasons.
One important mechanism is that blood draining from visceral fat travels directly to the liver through the portal vein. Excess fatty acids reaching the liver can contribute to fat accumulation and metabolic dysfunction.
Visceral fat also produces inflammatory chemicals that may promote insulin resistance and chronic low-grade inflammation.
In addition, fat can accumulate in organs where it should not normally be stored, including the liver, pancreas, heart and kidneys.
The Framingham Heart Study found that higher levels of visceral fat were more strongly associated with metabolic syndrome than subcutaneous fat, highlighting its greater impact on cardiometabolic health.
Health Conditions Linked to Excess Visceral Fat
Excess visceral fat has been associated with:
- Type 2 diabetes
- High blood pressure
- Coronary heart disease
- Stroke
- Abnormal cholesterol levels
- Fatty liver disease
- Chronic inflammation
The American Heart Association considers visceral adiposity an important risk factor for cardiometabolic disease because of its links with insulin resistance and ectopic fat deposition.
Can You Be Thin and Still Have Too Much Visceral Fat?
Yes. One of the biggest misconceptions is that only people who are overweight carry excess visceral fat.
'Individuals with higher visceral fat can appear to be average or even thin when looking in the mirror but have a disproportionate amount of fat around their abdomen,' Dr Al-Deek said.
This phenomenon is sometimes called 'normal-weight obesity' or being 'fat on the inside'.
Two people with the same body mass index (BMI) can have very different amounts of visceral fat. Someone with a normal BMI but a relatively large waist circumference may still face increased metabolic risk.
Why Waist Circumference Matters
Because BMI does not distinguish between muscle and fat or show where fat is stored, waist measurements can provide useful additional information.
Dr Al-Deek said waist circumference acts as a practical marker of abdominal fat.
Commonly used thresholds indicating increased cardiometabolic risk are:
- Men: 40 inches (102 cm) or more
- Women: 35 inches (88 cm) or more
Another useful measure is waist-to-height ratio, with many experts recommending keeping waist circumference to less than half of height.
What Causes Visceral Fat To Build Up?
Several factors influence where fat is stored.
Genetics
Genetics appear to play a major role in determining fat distribution, with heritability estimates ranging from 30% to 55%.
Physical Inactivity
Lack of exercise contributes to muscle loss and poorer glucose handling, both of which are linked with increased visceral fat.
Diet
Diets high in ultra-processed foods, refined carbohydrates and excess calories are associated with greater visceral fat accumulation.
Sleep And Stress
Chronic stress and inadequate sleep can promote fat storage around the abdomen.
Dr Al-Deek noted that sleep deprivation may increase abdominal fat deposition, particularly when combined with a high-fat, high-sugar diet.
Why Belly Fat Often Increases With Age
Many people notice that fat gradually shifts towards the abdomen as they get older.
Loss of muscle mass, reduced physical activity and hormonal changes all contribute.
Women often experience increased visceral fat during the menopausal transition as oestrogen levels decline.
The Study of Women's Health Across the Nation (SWAN) found that fat gain accelerates around menopause while muscle loss also increases, leading to greater abdominal fat accumulation.
Men also tend to accumulate more visceral fat with age, particularly if they become less active.
How Is Visceral Fat Measured?
CT scans and MRI scans are the most accurate methods for measuring visceral fat, but they are mainly used in research because they are expensive and, in the case of CT, involve radiation exposure.
In everyday clinical practice, doctors are more likely to use:
- Waist circumference
- Waist-to-height ratio
- Body composition scans such as DEXA in some settings
These simpler measures provide useful information about abdominal fat and metabolic risk.
The Best Ways to Reduce Visceral Fat
Dr Al-Deek described exercise as 'one of the most potent weapons in our arsenal in the fight against visceral obesity'.
Research suggests high-intensity interval training (HIIT) may be particularly effective for reducing visceral fat, followed by combined aerobic and resistance training.
Aerobic exercise helps increase overall energy expenditure, while resistance training preserves or builds muscle mass, which is important for metabolic health.
Is 150 minutes a week enough?
Yes. Around 150 minutes of moderate-intensity exercise per week, such as brisk walking, cycling or swimming, is enough to produce meaningful reductions in visceral fat for many people.
Importantly, exercise can reduce visceral fat even if body weight changes little.
'Someone might not be losing weight but is still improving their body composition by reducing waist circumference, increasing muscle mass and improving metabolic health,' Dr Al-Deek said.
What Should You Eat?
No food specifically burns belly fat, but certain dietary patterns are associated with lower visceral fat levels.
The Mediterranean diet, which emphasises vegetables, fruit, whole grains, legumes, nuts, olive oil and fish, has consistently been linked with reduced cardiometabolic risk.
Healthy lower-carbohydrate diets may also help reduce waist circumference and visceral fat in some people.
The key is a sustainable eating pattern that supports a healthy body composition rather than a single 'fat-burning' food.
What About Supplements?
Dr Al-Deek cautioned that supplements and fat-burning pills should not be viewed as a solution for visceral obesity.
While some products may modestly affect appetite or weight, they are not recommended as a standalone treatment.
Lifestyle measures remain the foundation for reducing visceral fat.
Conclusion
Visceral fat is different from the fat stored under the skin because it sits around vital organs and actively influences metabolism, inflammation and insulin sensitivity.
Excess visceral fat is linked with diabetes, heart disease and fatty liver disease, and it can affect people who appear slim as well as those who are overweight.
Measuring waist circumference, staying physically active, building muscle, eating a healthy diet, sleeping well and managing stress are among the most effective ways to reduce visceral fat and improve long-term health.