Does excess weight really make your hormones worse?

Insulin resistance is the most solid and best-supported hormonal change associated with excess weight. Adipose tissue disrupts the sensitivity of cells to insulin, forcing the pancreas to produce ever-increasing amounts of insulin. If that pattern continues, the risk of type 2 diabetes rises considerably. This applies to both children and adults.

Fat cells also produce the hunger hormone leptin. In people with excess weight, leptin levels are chronically elevated, but the body adapts to them and responds to them less and less. As a result, the 'I am full' signal works less effectively, making weight management even harder.

For women, there is a clear effect on fertility. Obese women have up to three times the likelihood of absent or irregular ovulation. If you also have PCOS (a common hormonal condition in women), extra weight generally makes symptoms worse and further increases the risk of reduced fertility.

In children with excess weight, there is also an association with earlier puberty, particularly in girls. Elevated leptin levels appear to play a role here. Regarding thyroid function and cortisol (the stress hormone), some studies do observe changes, but the evidence is more contradictory and the precise cause-and-effect relationship is not yet clear.

An important caveat: BMI explains only about 17% of the risk of insulin resistance. Genetic factors and socioeconomic circumstances are at least equally determining. Excess weight is therefore a real risk factor for hormonal disruptions, but not the only one. What does hold true is this: the more visceral fat (the fat surrounding the organs), the more chronic low-grade inflammation, and that inflammation in turn is a driver of insulin resistance and organ damage.