After a Hard Day's Work, Why Does a Pizza Seem So Tempting?

Now, we have the reason why a pizza or a chocolate cake seems such an enticing prospect after a stressful day at work.

A new animal study has found that exposure to stress post dieting can increase chances of binge eating.

Researchers at the University of Pennsylvania examined the behaviour and hormone levels of mice on limited diets. After three weeks of fewer calories, the mice lost 10 to 15 percent of their body weight, similar to human diet weight loss.

"Yo-yo dieting" - temporarily losing weight only to regain it, plus more - is a well-known phenomenon.

Tracy Bale and her colleagues found the mice had increased levels of the stress hormone corticosterone and displayeddepression-like behaviour. The authors also discovered that several genes important in regulating stress and eating had changed.

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.

"These results suggest that dieting not only increases stress, making successful dieting more difficult, but that it may actually 'reprogram' how the brain responds to future stress and emotional drives for food," Bale said.

"This study highlights the difficult road that human dieters often travel to attain and maintain their weight loss goals. It also suggests that management of stress during dieting may be key to achieving those goals," said Jeffrey Zigman at the University of Texas.