What does chronically high cortisol do to your belly fat and blood sugar?
Chronically high cortisol directs fat toward the abdominal cavity and increases the risk of insulin resistance and type 2 diabetes. If you experience prolonged high levels of stress, that is an additional reason to actively address it.
Cortisol actively directs fat toward the abdominal cavity. This has been well documented in people with an adrenal tumour that produces cortisol autonomously: even a mild elevation in cortisol led, after roughly three years, to significantly more visceral belly fat. Notably, the ratio of deep abdominal fat to subcutaneous fat was just as high as in patients with full-blown Cushing's syndrome, the condition in which the adrenal glands structurally produce too much cortisol. Cushing's syndrome is also the only known hormonal disorder that specifically causes this abdominal fat pattern. An underactive thyroid or other hormonal disorders do cause weight gain, but not in this location.
Cortisol does not act alone. When testosterone and growth hormone are simultaneously low, the effect is amplified: fat ends up even more strongly in the abdominal cavity than under the skin. This pattern is seen in people with a high waist-to-hip ratio and in those under prolonged stress, where the hormonal balance becomes chronically disrupted.
That belly fat in turn is harmful to your blood sugar. Visceral adipose tissue releases free fatty acids into the liver, and these disrupt how well the body's cells respond to insulin. The result is rising blood sugar, and visceral fat is therefore considered a strong predictor of type 2 diabetes.
Chronic stress also makes it harder to eat less. Cortisol influences reward centres in the brain and increases the tendency to choose fattier and more sugar-rich foods. Under normal circumstances, satiety hormones such as leptin and insulin suppress this effect, but with prolonged high cortisol that system becomes dysregulated. The result is greater appetite, more calories consumed, and even more belly fat. Psychosocial stress, such as a persistent sense of social pressure or tension, is also associated with a higher waist-to-hip ratio and signs of an overactive stress response, although direct causal evidence for this in humans is limited.
Claims are based on studies in people with adrenal tumours (autonomous cortisol), patients with Cushing's syndrome, epidemiological research on waist-to-hip ratio and hormonal profile, and mechanistic/animal research on stress and eating behaviour. One claim (psychosocial stress) is largely associative and based on animal models.