Women with overweight and class I obesity appear to have the lowest cortisol levels, while more significant obesity appears to be associated with higher cortisol levels, according to recent findings.
In the cross-sectional study, Karen K. Miller, MD, of Massachusetts General Hospital, and colleagues evaluated 60 premenopausal women aged 18 to 45 years: 28 with overweight or obesity, 18 with anorexia nervosa and 21 healthy controls at normal weight. Overweight was defined as BMI 25 to 29.9 kg/m2, and obesity was classified as class I (30-34.9 kg/m2) and class II (35-39 kg/m2).
Karen K. Miller
Anorexia nervosa was classified based on DSM-IV criteria, which includes extreme fear of weight gain, body image dysmorphia, weight that is 85% of ideal body weight and cessation of menstruation for 3 consecutive months. Participants were asked to collect 24-hour urine samples, in addition to 11 p.m. and 7 a.m. salivary samples within 1 week of an inpatient hospital visit. For each sample, researchers assessed creatinine clearance, and urinary free cortisol/creatinine clearance was calculated for each specimen to account for the decreased creatinine and filtered cortisol linked to anorexia nervosa.
During the inpatient visit, participants underwent placement of an IV catheter and fasting blood was sampled every 20 minutes from 8 p.m. to 8 a.m. Fasting cortisol and cortisol binding globulin concentrations were measured at 8 a.m. Participants were asked to take 5 g of oral dexamethasone every 6 hours for 48 hours to decrease endogenous disparities in cortisol levels.
The researchers found that with the exception of dexamethasone-suppression-CRH testing, all cortisol measures exhibited a U-shaped association with BMI, most notably urinary free cortisol/creatinine clearance (P = .0004) and mean overnight serum cortisol (P < .0001).
The lowest cortisol levels were seen in the overweight-class I obesity range, and these were also associated with visceral fat tissue and total fat mass. Participants with anorexia nervosa had higher mean cortisol levels than participants with overweight or obesity. Attenuated inverse relationships were seen between lean mass and some measures of cortisol, and most measures of cortisol were inversely related to posterior-anterior spine and total hip bone mineral density.
According to the researchers, these findings have not determined the precise nature of the relationship between cortisolemia, hypothalamic-pituitary-adrenal activation and adiposity.
“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,” the researchers wrote. – by Jennifer Byrne
The researchers report no relevant financial disclosures.