Yo-yo dieting increases risk of comfort eating as it changes how the body deals with stress
Published 01/12/2010 | 09:55
Yo-yo dieting can increase stress levels and make you more likely to reach for cake and biscuits after a hard day, new research has found.
The repeated loss and gaining of body weight – often at unhealthy rates – appears to reprogramme how the brain deals with stressful situations and cravings for food.
The effect is so profound that it changes the structure of DNA in areas known to release hormones designed to manage anxiety, the study discovered.
Researchers examined the behaviour and hormone levels of mice on limited diets and compared them with those on a normal diet.
After three weeks of fewer calories, the dieting mice lost 10 to 15pc of their body weight, similar to human diet weight loss.
But these rodents were also found to have increased levels of the stress hormone corticosterone and displayed depression-like behaviour.
The authors also discovered that several genes important in regulating stress and eating had changed.
Previous research shows that experiences can alter the form and structure of DNA, an effect known as epigenetics.
Even after the mice were fed back to their normal weights, the epigenetic changes remained.
To investigate whether those molecular changes might affect future behaviour, the researchers put the mice in stressful situations and monitored how much fatty foods they ate.
The previously restricted mice ate more high-fat food than normal mice.
Dr Tracy Bale, who led the researchers at the University of Pennsylvania, said: "These results suggest that dieting not only increases stress, making successful dieting more difficult, but that it may actually 'reprogramme' how the brain responds to future stress and emotional drives for food."
The findings illustrate the underlying mechanisms for why fatty and sugary food is so appealing after a stressful day at work.
The authors suggest that future weight loss drugs may target these stress-related molecules.
Dr Jeffrey Zigman, an expert in endocrinology, diabetes, and metabolism at the University of Texas Southwestern Medical Center, said the conditions the mice experienced mimic the type of psychosocial stress that people often experience.
"This study highlights the difficult road that human dieters often travel to attain and maintain their weight loss goals," Dr Zigman said.
"It also suggests that management of stress during dieting may be key to achieving those goals."
The research was published in the Journal of Neuroscience.