How does your body fat affect hormone production as you get older?
Body fat has a considerable influence on your hormonal balance as you age: more abdominal fat disrupts insulin sensitivity, and conversely, lower oestrogen or testosterone levels worsen fat accumulation around the abdomen. Exercise and maintaining a healthy weight are the most concrete levers you have within your own control.
Fat tissue is not a passive storage depot: it actively produces hormone-like proteins called adipokines. When a person is overweight, this system becomes dysregulated and the fat produces too many pro-inflammatory substances. The result is a smouldering chronic inflammation that makes itself felt throughout the entire body.
After menopause, oestrogen levels drop sharply, and that has direct consequences for where fat accumulates. Oestrogen normally directs fat to the hips and thighs, a pattern that is favourable for the heart. Without oestrogen, storage shifts to the abdomen. That abdominal fat (visceral fat) breaks down more rapidly and sends large quantities of free fatty acids into the bloodstream. Because oestrogen loss also suppresses the burning of those fatty acids, they build up, increasing the risk of insulin resistance and type 2 diabetes.
In men, testosterone plays a comparable role: it inhibits the accumulation of abdominal fat and supports muscle growth and cellular sensitivity to insulin. Part of this effect operates through the conversion of testosterone to oestradiol. When testosterone levels decline with age, abdominal fat increases and metabolism deteriorates in the same way as in women after menopause.
Brown adipose tissue, a distinct type of fat that burns energy as heat, also decreases with age. This goes hand in hand with poorer temperature regulation and greater insulin resistance. There are preliminary indications from animal studies and observational studies that this also affects the brain, but this has not yet been well established in humans.
One point of concern with potent weight-loss medications (such as semaglutide) is that they reduce not only harmful visceral fat but also the subcutaneous fat of the face. That facial fat produces growth factors that keep the skin looking young. Losing it can have a visibly ageing effect. This has so far only been described in observations, not in controlled studies.
All claims are based on observational and mechanistic research, partly supplemented by reviews. There are no large randomised trials among the sources. The level of evidence is moderate to limited.