Reading aloud US researchers have discovered why it is so hard to resist unhealthy treats following a diet, especially during stress: relinquishing food programs the brain and modifies various genes responsible for responding to stress. As a result, sufferers tend to eat more fatty foods in stressful times - fueling the dreaded yo-yo effect that causes them to regain more weight after a diet than they previously had. Although the scientists have so far only been able to show the effect in mice, they are certain that there is such a connection in humans as well. It could therefore be worthwhile to target the stress response in order to support those who want to lose weight, and possibly even to influence them, write Tracy Bale from the University of Pennsylvania and her colleagues. For three weeks, the researchers' test mice had to diet. After that time, the animals had lost about 10 to 15 percent of their original body weight - a level that people typically achieve on a successful diet. However, the mice did not do well: the levels of stress hormone in their blood were significantly increased and they showed a behavior that indicated a depressive mood.
This was evidently attributable to changes in various genes involved in the regulation of stress and the control of food intake, the scientists were able to show. These were so-called epigenetic changes in which chemical switches are attached to the genetic material that turn genes on or off. This only affects the activity of a gene and not its blueprint. Nevertheless, such changes are permanent and can even be passed on to the offspring.
The current mouse experiment also showed that the effect was not only effective during the actual diet phase, but also later, when the mice regained their original weight: they were under stress and approved the previously dieted ones Mice significantly more high-fat food than their conspecifics who had not dieted. "The results suggest that dieting not only increases stress levels, making successful weight loss more difficult. Rather, a diet does seem to actually re-program how the brain responds to future stress, "Bale comments. In the future, drugs targeting this mechanism may help dieters to persevere and possibly prevent the later onset of the yo-yo effect.
Tracy Bale (University of Pennsylvania) et al .: Journal of Neuroscience, Vol. 30, No. 48 dapd / science.de? IlkaLehnen-Beyel advertisement