Researchers at the Massachusetts General Hospital recently reported a link between cortisol levels and different weight ranges in women. The study was published in the Journal of Clinical Endocrinology and Metabolism and is entitled “Cortisol Measures Across the Weight Spectrum.”
The hypothalamic-pituitary-adrenal (HPA) axis is a complex system that involves three endocrine glands: the hypothalamus, the pituitary gland and the adrenal glands. The HPA axis regulates the body’s reactions to stress, the immune system, digestion, mood and emotions, as well as energy storage and expenditure. The activity of the HPA axis has been associated with alterations in body composition, including cortisol levels. Cortisol is a hormone released in response to stress and low blood glucose levels. It can increase blood sugar levels, suppress the immune system, decrease bone formation and assist on the metabolism of compounds like fat and proteins.
Conflicting data has been reported regarding a possible link between the HPA axis and obesity. The most reliable finding in studies so far is that there is an inverse correlation between cortisol levels and the body mass index (BMI), where a low BMI is correlated with a high cortisol measure.
The goal of the study was to assess the cortisol levels in individuals with different weight ranges. In total, the team analyzed a cohort of 60 pre-menopausal women, aged 18 to 45 years, from which 21 were overweight or obese (OB group), 21 who had a normal weight (control group), and 18 who suffered from anorexia nervosa (AN group), a psychiatric disorder characterized by food restriction regardless of the usually extremely low fat mass and body weight of the individual.
Researchers observed that overall the cortisol measures assessed exhibited a U-shaped relation with BMI, where the lowest and highest BMI had the highest cortisol levels. The mean cortisol levels were found to be higher in the AN group in comparison to the OB group. The lowest cortisol levels were found among the overweight-class I obese women (BMI of 30-34.9 kg/m2), being linked to visceral adipose tissue and total fat mass. The team also observed an inverse correlation between bone mineral density and cortisol measures.
The research team concluded that overweight-class I obese women have the lowest cortisol measures, and that in more significant obesity grades the cortisol levels rise, although not as high as in women with anorexia. The authors suggest that extreme underweight and overweight states may activate the HPA axis, leading to hypercortisolemia (excess serum levels of cortisol) that may ultimately contribute to increased adiposity, decreased bone mineral density and muscle wasting.
The team emphasizes that the exact relationship between the HPA axis, hypercortisolemia and adiposity still needs to be elucidated. “The [hypothalamic-pituitary-adrenal] axis activation associated with obesity and excess adiposity raises the question of whether hypercortisolemia contributes to increased adiposity in the setting of caloric excess, whether increased adiposity drives [hypothalamic-pituitary-adrenal] activation, or whether the relationship between hypercortisolemia and adiposity is bidirectional,” wrote the research team according to a news release.
