How dangerous is belly fat?

Belly fat, and visceral fat in particular (the fat that sits deep in the abdominal cavity around the organs), is strongly linked to cardiovascular disease. Multiple epidemiological studies confirm this association, and it is better supported than the link between liver fat and heart disease (PMID 39235730). A large Chinese cohort study with more than 8,000 participants over nine years shows that people with a lot of belly fat had a 75 to 87 percent higher chance of developing cardiovascular disease than people with little belly fat (PMID 39604987). Notably, the risk was actually highest in people with a lot of belly fat but without the classic accompanying metabolic problems such as insulin resistance. This shows that belly fat is dangerous in its own right, independent of other risk factors.

Belly fat also increases the risk of other conditions. In an American sample of more than 5,000 people, those with the most belly fat (measured using the so-called Body Roundness Index, a measure of abdominal roundness) had more than three times the chance of developing gallstones compared with those with the least belly fat (PMID 38840060). This was a cross-sectional study, meaning that cause and effect have not been proven, but the association is strikingly large. Furthermore, a low ratio of muscle mass to visceral fat is strongly associated with fatty liver disease: people with little muscle and a lot of belly fat had nearly four times the chance of this liver condition (PMID 38751375). This underlines that not only losing weight, but also building muscle mass, may be important.

Visceral fat also leaves visible traces in the body's biology. A large study with nearly 17,000 participants and tens of millions of protein measurements showed that the amount of belly fat can be read back in the pattern of proteins in the blood (PMID 31792462). This is not yet a method used in clinical practice, but it illustrates how profound the effects of belly fat are. Note that several authors of this study work for the company that sells the measurement technology, which represents a potential conflict of interest.

There is good news regarding treatment. Lifestyle changes help: a combination of the Mediterranean diet (rich in legumes and plant-based foods) and approximately two hours of exercise per week significantly reduced visceral belly fat after 12 weeks in people over 50 with a high cardiovascular risk (PMID 39125324). Exercise or diet alone did not have this effect. The drug liraglutide, a so-called GLP-1 agonist similar to the better-known semaglutide, reduced visceral fat by an average of 12.5 percent in a randomised study of 36 weeks, compared with 1.6 percent in the placebo group (PMID 34358471). An important caveat: nearly half of the medication users experienced gastrointestinal complaints, and the study was funded by manufacturer Novo Nordisk, which may cast a positive light on the results.