Scientists Find Evidence of Grim Long-Term Effects of Fad Diets
In a new study published in the journal Advanced Science, researchers from France's University of Rennes and Paris-Saclay University found, after conducting a series of studies with mice, that yo-yo diets appeared to result in long-lasting changes to their gut bacteria.
Also known as "weight cycling," this form of dieting often involves people taking on restrictive — and often extreme or trendy — plans to lose weight, only to get so hungry from such the vast and unsustainable change in their habits that when they go back to the way they ate before, they end up eating too much, and gaining back all the weight and then some.
While it's well known that yo-yo dieting is a bad idea compared to making sustainable choices to eat healthier foods, recent studies have begun to show its links to other detrimental health effects, including increased risk of kidney and heart disease and hormonal changes that can slow down the metabolism.
In their new study, the researchers from Rennes and Paris-Saclay simulated human yo-yo dieting by alternately feeding mice a higher-fat and higher-sugar diet reminiscent of those eaten by the modern Westerner and one that was lower fat, over a period of several weeks.
When they were switched back onto the richer diet, the mice started showing signs of binge eating. Not only was this effect seen in the mice who were subjected to the yo-yo diets, but also to rodents who had eaten healthier food but were implanted with "altered" gut bacteria from the other mice.
Curiously, the French researchers also found that shifts in the rodents' diets appeared to change their relationship to food as well, adding to the body of evidence that fad diets and the yo-yo effect they instill could be considered a form of disordered eating.
"By carefully analysing the brain patterns of the mice on the dieting schedule, the researchers could see that they were probably eating for pleasure rather than because they were hungry," a press release about the study notes, "as if the brain's reward mechanism had been rewired."
While it's far too soon to tell whether that effect will be replicable in humans, anyone who's experienced the yo-yo dieting effect personally can attest that that first bite of a burger or fries after going weeks without is indeed very, very satisfying.
More on mice studies: Scientists Gene Hack Mice So Their Livers Produce Their Own Ozempic-Like Drug
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