Not all body fat is created equal. The fat you can pinch on your arms, thighs, and hips — subcutaneous fat — is relatively benign from a metabolic standpoint. But the fat packed deep inside your abdomen, wrapping around your liver, pancreas, and intestines, is a different story entirely. This visceral fat behaves almost like a rogue organ, actively pumping inflammatory chemicals into your bloodstream and dramatically increasing your risk of serious disease.
Subcutaneous fat sits between the skin and the muscle wall. It serves as insulation, energy storage, and cushioning. While excess amounts are not ideal, this type of fat is relatively metabolically inert — it largely minds its own business.
Visceral fat (also called intra-abdominal fat) accumulates inside the abdominal cavity around the internal organs. Unlike subcutaneous fat, visceral fat is highly metabolically active. It secretes a cocktail of inflammatory molecules called adipokines, including tumour necrosis factor-alpha (TNF-α), interleukin-6 (IL-6), and resistin, which interfere with insulin signalling and promote chronic low-grade inflammation throughout the body.
Chronic low-grade inflammation is now understood to be a central driver of many of the diseases that dominate modern mortality: cardiovascular disease, type 2 diabetes, certain cancers, non-alcoholic fatty liver disease, and even Alzheimer's disease.
Visceral fat is one of the primary sources of this inflammation. The adipokines it releases enter the portal vein — a direct highway to the liver — where they promote insulin resistance, increase triglyceride production, and impair the liver's ability to regulate blood sugar. Over time, this contributes to metabolic syndrome: a cluster of conditions including high blood pressure, elevated blood sugar, excess abdominal fat, and abnormal cholesterol levels.
Two people can weigh the same, stand at the same height, and have identical BMIs — yet one may have twice the visceral fat of the other. BMI is completely blind to fat distribution. This is why someone can be classified as "normal weight" by BMI while harbouring dangerous levels of visceral fat — a condition researchers call "TOFI" (Thin Outside, Fat Inside).
Metrics like WHtR and waist-to-hip ratio are better at flagging visceral fat because they measure abdominal circumference, which correlates strongly with visceral fat volume on imaging studies.
Research has linked excess visceral fat to a wide range of conditions. Cardiovascular disease is the most well-established risk — visceral fat accelerates atherosclerosis (hardening and narrowing of the arteries). Type 2 diabetes risk rises sharply as visceral fat impairs insulin function. Non-alcoholic fatty liver disease occurs when visceral fat deposits in and around the liver. Certain cancers, including colorectal and breast cancer in postmenopausal women, are associated with higher visceral fat levels. There is also growing evidence for links to dementia and Alzheimer's disease.
Genetics play a role — some people are predisposed to storing fat viscerally rather than subcutaneously. Hormonal changes, particularly the decline in oestrogen during menopause and decreasing testosterone in ageing men, shift fat storage toward the abdomen. Chronic stress elevates cortisol, which preferentially directs fat to visceral depots. A sedentary lifestyle and diets high in refined carbohydrates and alcohol also promote visceral fat accumulation.
The good news is that visceral fat is often the first type of fat to be mobilised during weight loss. Regular physical activity — especially a combination of aerobic exercise and resistance training — is one of the most effective interventions. Even without weight loss on the scale, exercise can significantly reduce visceral fat volume.
Dietary changes that reduce refined carbohydrates, added sugars, and excessive alcohol while increasing fibre, protein, and whole foods have also been shown to preferentially target visceral fat. Adequate sleep (7–9 hours) and stress management are important supporting factors, as chronic sleep deprivation and elevated cortisol both promote visceral fat storage.
While imaging techniques like CT and MRI scans are the gold standard for measuring visceral fat, simple tape-measure metrics provide good screening at home. A WHtR above 0.5 suggests excess abdominal fat. A high waist-to-hip ratio (above 0.9 for men, 0.85 for women) indicates an apple-shaped fat distribution associated with visceral fat. These are not diagnostic, but they are useful signals to discuss with your doctor.