Long-Term Stress Link to Obesity

Nicky Broyd

February 27, 2017

Long-term stress may make you more likely to be obese according to new research by scientists at UCL (University College London).

Anecdotally stress has long been associated with comfort eating and weight gain. This latest scientific research set out to look at obesity and long-term stress levels by measuring the amount of the stress hormone cortisol found in hair.

The Study

Cortisol is a hormone which regulates the body’s response to stress and plays an important role in metabolism and determining where fat is stored.

Previous studies looking at the link between cortisol and obesity mainly relied on measurements of the hormone in blood, saliva or urine which failed to capture long-term levels.

Scientists at UCL decided to use a different, and relatively new, method – examining hair samples.

They took a lock of hair 2cm long from each participant. It was cut as close as possible to the scalp and represented approximately 2 months’ hair growth along with accumulated levels of cortisol. They also examined the participants’ weight, BMI ( body mass index), waist measurement and looked at how hair cortisol related to the persistence of obesity over time.

Their research involved 2,527 men and women aged 54 and older taking part in the English Longitudinal Study of Ageing, taking data over a 4 year period.


The research, published in the journal Obesity, found that people with higher levels of cortisol in their hair tended to have larger waist circumference measurements and were heavily, and more persistently, overweight.

Individuals classified as obese on the basis of their BMI (≥30) or waist circumference (≥102cm in men, ≥88cm in women) had particularly high levels of hair cortisol.

Dr Sarah Jackson who led the research says in a press release: "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."

Study Positives and Negatives

On the positive front, this was a large, nationally representative study looking at data over 4 years.

However, there were limitations, including the fact the people studied were older (average age nearly 68) and almost exclusively white British (98%). Also the study did not account for the use of medication that might influence cortisol concentration.

It is not currently known what comes first, the stress or the obesity, or in study speak, whether chronically elevated cortisol levels are a cause or a consequence of obesity, so more research is necessary.


UCL Press Release

Study: Hair Cortisol and Adiposity in a Population-Based Sample of 2,527 Men and Women Aged 54 to 87 Years