Cortisol may contribute to obesity by interacting with regulators of weight and food intake. Leptin, the satiety hormone is secreted by fat cells in order to inform the brain of fat levels in the body and to control eating. High levels of leptin result in an inhibition of hunger. A study that removed the adrenal gland in mice with low levels of leptin found that these mice lost weight, suggesting that glucocorticoids may contribute to leptin metabolism (Dubuc & Wilden, 1986).
Another study found that administration of a steroid medication, dexamethasone, increased leptin levels when administered after eating in both average and obese patients (Laferrère, et al., 2002; Laferrère, Fried, Osborne, & Pi-Sunyer, 2000; Dagogo-Jack, Selke, Melson, & Newcomer, 1997). Ghrelin, the hunger hormone, induces feelings of hunger and promotes food intake. This hormone has been found to have an inverse relationship with cortisol during fasting, suggesting that cortisol may be used to mediate the effects of ghrelin. However, more research is needed before any solid conclusions can be drawn.
Based on the previous evidence, it’s not a surprise that researchers have been investigating the link between stress and hunger. This association is also likely due to the fact that dysregulation of the HPA has been associated with multiple eating disorders such as binge eating disorder, bulimia and anorexia. Changes in cortisol metabolism have also been associated with changes in peptides involved in food regulation like insulin.
Links between cortsiol, stress, sleep, and obesity
Cortisol also has an influence on sleep, evident by the studies linking obesity and sleep deprivation. Sleep deprivation has been shown to be associated with increased body mass index (BMI) and increased risk for obesity and diabetes. This association between sleep deprivation and obesity is thought to occur because sleep deprivation is considered a type of prolonged stress that may eventually lead to dysregulation of the HPA. Current studies on the topic have conflicting results, however.
Stress at an early age has also been associated with an increased risk for development of obesity. For example, a recent study found that macaque monkeys were more likely to weigh more and have a higher body mass index if their mother was exposed to food insecurity while her offspring were young. In fact, there is even evidence that significant malnutrition during pregnancy resulting in low birth weight increases the risk of obesity development in the offspring.