The study, carried out by researchers at the University of Pennsylvania and led by Dr. Tracy Bale, examined hormone changes and behaviors of mice fed a calorie-restricted diet that produced a 10-15 percent weight reduction over three weeks.
Withdrawal from a high-fat diet has previously been shown to cause stress levels to increase, and in this study the dieting mice had higher levels of the stress hormone corticosterone and showed symptoms of depression in stressful situations. In addition, the mice had altered DNA after dieting, with changes in the genes that control appetite and stress – and those changes remained even after they were fed back to their pre-diet weights. Previously restricted mice showed unusually high levels of hormones that regulate appetite when given access to a high-fat diet, leading to stress-induced binge eating.
"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.
The authors wrote that although previous research has focused on health benefits for those who have lost weight in the long-term through calorie restriction, including longer lifespan, “examination of the stress sensitivity during caloric restriction has been neglected”.
They wrote that because humans do not usually live in a restricted environment, stress level indicators could be important in determining the likelihood of long-term dieting success.
The researchers added that although binging on high-fat foods when they are available could be a helpful behavior in times of famine, in a society with plentiful supplies of energy-dense food it is likely to make weight management difficult.
Source: Journal of Neuroscience
December 1, 2010 • 30(48):16399 –16407
“Caloric Restriction Experience Reprograms Stress and Orexigenic Pathways and Promotes Binge Eating”
Authors: Diana E. Pankevich, Sarah L. Teegarden, Andrew D. Hedin, Catherine L. Jensen, and Tracy L. Bale