For some time, studies have shown a link between elevated stress and obesity. Measuring cortisol levels in the hair may be a better way to evaluate chronic stress, since the hormone level will not fluctuate from day to day.
More and more studies suggest a link between chronic stress and obesity, and researchers reporting in Obesity have found a unique way to measure this connection: by studying cortisol levels in people’s hair.
Cortisol is a steroid hormone that elevates the body’s antistress and anti-inflammatory responses. It is most associated with the “fight or flight” response, and small increases can bring an energy boost and enhanced concentration. But elevated cortisol levels for extended periods increase insulin resistance and have other harmful effects, including short-term memory loss.
By taking a snippet of hair close to the scalp—at least 2 cm in length—researchers found a way to measure free cortisol over the past 2 months, which offers a more reliable assessment of chronic stress than measuring the hormone in saliva, urine, or blood, which can fluctuate daily or hourly.
Hair samples, along with measurements of height, weight, and waist circumference, were taken from 2257 men and women aged 54 and older who were already taking part in the English Longitudinal Study of Aging. Researchers also evaluated patients’ socioeconomic status, whether they smoked, and whether they had diabetes or arthritis.
High concentrations of cortisol were associated with weight, waist circumference, and body mass index (BMI), and were significantly elevated in those who were obese (BMI at least 30 kg/m2). Hair cortisol levels were also slightly higher in those with diabetes, but did not differ for those with arthritis.
A major finding of the study: Those who had elevated cortisol levels over time were likely to have persistent obesity, which researchers could conclude because they had BMI measures taken 4 years apart. In fact, those with BMI above 30 at both time points had the highest cortisol levels.
“This suggests that chronic high-level cortisol exposure may play a role in the maintenance of obesity,” they wrote.
More studies are needed to study any long-term associations of cortisol and being obese, they say. If chronic exposure to cortisol is found to be a cause, then “targeting cortisol levels may offer a novel method for treating obesity.”
Jackson SE, Kirschbam C, Steptoe A. Hair cortisol and adiposity in a population-based sample of 2527 men and women aged 54 to 87 years [published online February 23, 2017]. Obesity. doi: 10.1002/oby.21733.