At least that’s what seems to happen in mice. As summarized in US News and World Report,
Shaving calories triggers molecular changes in the brain that make mice more susceptible to stress and binge eating long after the diet ends, researchers report in the Dec. 1 Journal of Neuroscience. The finding could explain part of the yo-yo dieting phenomenon, in which people repeatedly diet and lose weight but then subsequently regain even more than they lost.
Researchers found that the dieting mice were more stressed than the non-dieting mice. They also found that even after ending the “diet” and regaining the weight, the former-dieting mice were more susceptible to stress than the non-dieters.
The team traced lower activity of the gene that makes CRF to a chemical modification called DNA methylation. DNA methylation and other modifications to genes help to regulate gene activity. Dieting mice had lower levels of methylated DNA near the gene for CRF than did animals that continued on the high-fat diet or ones that ate as much regular chow as they wanted. This change was essentially locked in for the dieting mice. It did not increase even two months after the diet ended—a long time in the life of a mouse, and equivalent to years, maybe even decades, for a person.
Researchers mildly stressed the mice for a week with things like damp bedding, cage swaps or putting a marble in the cage—mice are not big fans of change—so that the animals didn’t know what was coming next. Under this mild, but chronic, stress the former dieters snarfed down far more of the high-fat food than the nondieters. And the ex-dieters also had higher levels of hormones that prompt eating.
I DID find it rather eye-rolling that the article suggests that “dieters may need to cut stress as well as calories”, given that being fat is itself stressful. And, of course, it remains to be seen how much of this applies to humans. But this may help explain the mechanisms by which dieters so often regain the lost weight.
Abstract is here.