Some scientists thought that fat around the organs might make too much of the stress hormone cortisol locally, which could make people gain weight—but after looking at many studies, it seems this probably isn’t a big reason for obesity.

Researchers looked at several genes related to stress hormones in fat tissue from women's bellies. They found that only one specific gene (11β-HSD1) in the omental fat was linked to belly fat obesity in women, even after accounting for other factors that might affect the results.

In Chinese adults, people with higher levels of a specific enzyme (11beta-HSD1) in their belly fat tend to also have higher body weight, as measured by BMI.

In men with belly fat, deep abdominal fat is linked to certain blood chemicals like PC 32:0, but under-skin fat isn't.

In women who have fat stored around their internal organs (visceral obesity), the fat tissue produces more of a specific enzyme and hormone related to stress compared to women without this type of fat buildup.

In women, higher levels of a specific enzyme (11β-HSD1) in fat tissue are linked to having more body fat, especially around the belly.