Using hair to measure long-term levels of the stress hormone cortisol, UK researchers confirmed the link between chronic stress and gaining weight, as well as difficulty shedding excess weight.
Previous research has tied high levels of cortisol in the blood, urine or saliva to obesity, but these measurements can vary based on factors like the time of day; they don’t capture long-term stress levels.
When people face a stressful situation, a chain reaction is set off in the body that results in the release of cortisol, leading to higher levels of this hormone in the body.
What does cortisol do?
Cortisol is involved in many biological processes, including metabolism, body composition and the accumulation of body fat. Plus, when we’re stressed out we may be less motivated to exercise or resist unhealthy foods.
Stress sets off alarms in the brain that trigger the nervous system to release hormones to sharpen the senses, tense the muscles, speed up the pulse and deepen breathing. Commonly called a “fight or flight” response, this biological reaction helps us defend ourselves in threatening situations.
Isolated or temporary stressful situations may not be harmful, but routine exposure to stress can lead to immune system problems, heart disease, nervous system complications, mental health disorders and obesity.
For the study, researchers examined data collected from men and women, aged 54 and older, taking part in the English Longitudinal Study of Ageing. Participants underwent tests every two years starting in 2002, and during the sixth wave of the study they provided a hair clipping.
Obese people had high cortisol levels
The study team tested cortisol levels that accumulated in the hair over time in 2,527 men and women and found that participants with more cortisol in their hair were also more likely to be obese or have excess fat around their midsection.
Researchers looked at cortisol levels in the two centimeters of hair closest to the scalp, which typically represents about two months’ growth. They also looked at weight, waist circumference and body mass index (BMI), a measure of weight relative to height.
Participants who were classified as obese based on their BMI or waist circumference had particularly high levels of hair cortisol, the study found. Analyzing weight and body fat data from assessments in the four years prior to when the hair clipping was taken, researchers also found that obesity tended to persist over time for the people with the highest cortisol levels.
The study wasn’t a controlled experiment designed to prove how stress directly impacts cortisol levels or weight gain.
Even so, the findings add to growing evidence linking stress to obesity. Chronically high cortisol is thought to promote fat accumulation around the waist and increase the ability of fat cells to store fat.
Stress management, sleep important for weight loss
The solution for stressed out people looking to drop excess pounds isn’t clear from the study results, however.
There is not strong evidence or consistent studies showing that stress reduction itself causes weight loss. There is, however, accumulating evidence that sleep is very important; people overeat when under-rested.
The findings suggest that people may need to take a holistic approach to weight loss that goes beyond diet and exercise to consider factors like stress.
For some people, the priority might be learning to manage stress better so they are more able to follow a healthy eating plan and exercise.
Source: Obesity, online February 23, 2017.
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