Add this to the continually expanding list of ways your gut can affect your health: A new study indicates that changes to your microbiome could be the cause behind the rapid weight gain that’s common with yo-yo dieting.
Researchers Eran Elinav and Eran Segal from the Weizmann Institute of Science in Israel came to that conclusion after replicating those dreaded fluctuations—which are all too familiar to The Biggest Loser contestants, for instance—using mice as subjects, The Atlantic reports.
The mice were first fed a high-fat diet for a month, to trigger weight gain. Then, they went back on their regular diet, and lost weight. But when the mice went back on a high-fat diet, they gained more weight than they did the first time around.
Despite the extra plumping, blood sugar and cholesterol levels, and even metabolic rates, were no different than when they started. The only part of the body that changed? The microbiome (AKA the trillions of microbes that live in your body).
“The same mechanisms that protect us might act against us and increase our tendency to accumulate fat.”
After gaining weight, certain species in their microbiomes became more common while others lagged, making their guts less diverse. Also key? The microbiomes didn’t quickly bounce back to normal after losing weight—it was a slow process.
So the researchers concluded that the changed gut made the mice more prone to gaining weight quickly when eating a poor diet.
“The microbiome could act as a buffer to preserve energy until the next feeding opportunity comes,” says lead researcher Elinav. But if the hunger leads to a binge, “the same mechanisms that protect us might act against us and increase our tendency to accumulate fat.”
Though clearly more research needs to be done, it’s a notable step in understanding why crash diets can lead to big-time weight gain—and in respecting the power of the gut.
Speaking of healthy microbiomes, these gut-healthy supplements could help you get your best skin ever. And this wellness practice may be able so solve your digestive issues for good.