DIETERS who drop a lot of weight quickly could be more likely to put all the pounds back on, and then some, because of changes in the way their brains respond to stress, a new study said. Researchers at the University of Pennsylvania, led by Tracy Bale, studied the behaviour and hormone levels of mice on restricted diets and found that stressed-out mice with a history of dieting ate more high-fat foods than similarly stressed mice that had not been on a diet. After three weeks on their reduced calorie diet, the mice in the study lost 10-15 percent of their body weight, similar to what humans can lose on a diet, says the study published in the Journal of Neuroscience.
Bale and her colleagues found that the mice had increased levels of the stress hormone corticosterone, and in a test where they were hung by their tails, they spent more time just hanging there, immobile, than the control mice. The researchers called that “depressive-like behaviour.”
The researchers also found that several genes that play a key role in regulating stress and eating patterns had changed in the dieting mice.
Previous research has shown that experiences can alter the form and structure of DNA, an effect known as epigenetics. –MI
Even after the mice were allowed to eat their fill and had returned to their normal weights, the epigenetic changes remained, the study found. –MI