Hair study links long-term stress to increased risk of obesity

Stressed people are more likely to become obese over time and place themselves at risk of type 2 diabetes, researchers have discovered.
People plagued by anxiety and worry are more likely to gain weight, University of College London researchers concluded, following an innovative approach to studying cortisol, the hormone responsible for regulating responses to stress.
Cortisol also plays a significant role in metabolism and fat storage. Up until now it has been examined through saliva, blood and urine samples, but these only highlight short-term readings.
To address this, the researchers measured levels of cortisol in hair, taking 2cm samples from more than 2,500 people during the four-year study period.
Locks of hair representing two months of growth were taken from near to the scalp. The weight, waistline and Body Mass Index (BMI) of participants were also measured.
People in the obese category – whose BMI was 30 or higher or whose waists measured over 102cm in men or 88cm for women – had high levels of cortisol in their hair.
Lead researcher Dr Sarah Jackson said: “These results provide consistent evidence that chronic stress is associated with higher levels of obesity.
“People who had higher hair cortisol levels also tended to have larger waist measurements, which is important because carrying excess fat around the abdomen is a risk factor for heart disease, diabetes, and premature death.
“Hair cortisol is a relatively new measure which offers a suitable and easily obtainable method for assessing chronically high levels of cortisol concentrations in weight research and may therefore aid in further advancing understanding in this area.”
The researchers cited the fact that the people studied were 54 or older and white was a weakness of the study because cortisol levels tend to be higher in older people. They were also unable to establish whether obesity or stress developed first in participants.
The findings have been published in the journal Obesity.