A new study has found that the bacteria living in our gut—known as the gut microbiota—may play a key role in eating problems that come from repeated dieting.
This is the first time scientists have shown that gut microbes can directly influence binge-eating behavior caused by what’s often called yo-yo dieting. The research, done by scientists from France, was published in the journal Advanced Science.
Yo-yo dieting happens when someone goes on a low-calorie diet to lose weight but then returns to eating more normally or overeats, leading to weight gain. This cycle often repeats, with weight going up and down like a yo-yo. In Western countries, nearly half of all adults have tried low-calorie diets, and many of them experience this frustrating pattern.
While these diets may help in the short term, they often don’t work over the long term. Instead, they can lead to harmful behaviors like binge eating, where someone eats large amounts of food in a short time and feels out of control while doing it.
The team of researchers—from INRAE, CNRS, the University of Rennes, and Université Bourgogne Europe—wanted to find out why this happens. They were especially interested in how gut microbes might be involved. To test this, they ran experiments on mice.
First, they put mice on a cycle of two types of diets: one was a regular, healthy diet, and the other was high in fat and sugar—similar to fast food. The mice switched between these diets over time. The researchers noticed that the mice’s weight went up and down, just like in human yo-yo dieting.
Over time, the mice began to binge on the high-fat, high-sugar food whenever it was available, even when they had been fed enough. This showed that their eating habits had become unbalanced.
Next, the scientists looked at the gut bacteria of these binge-eating mice. They found that their microbiota had changed. To test whether these changes were important, they took stool samples (which contain gut bacteria) from the binge-eating mice and gave them to healthy mice who had never been on the diet cycle.
Surprisingly, after receiving the new gut bacteria, these healthy mice also started to binge eat fatty and sugary foods. This showed that the changes in gut microbes were enough to trigger this harmful behavior, even without the mice going through dieting themselves.
The researchers also studied the mice’s brains. They found higher activity in the parts of the brain linked to the reward system—this is the system that makes food taste especially good and makes us want to keep eating it.
There were also physical changes in the brainstem, which connects signals between the gut and brain. This suggests that the gut and brain were communicating differently because of the diet and the microbes.
These results are important because they show that dieting over and over again can have deep effects—not just on body weight, but on how the brain and gut work together.
It also means that people struggling with eating behaviors after dieting may be affected by more than just willpower or emotional eating—gut bacteria could be influencing their behavior without them even knowing it.
In conclusion, this study shows that the gut microbiota can directly influence binge-eating behavior triggered by yo-yo dieting. The gut microbes that changed during the diet cycles were able to pass on this binge-eating behavior to other healthy animals, suggesting a strong connection between the gut and brain.
It also showed that repeated dieting might not just be unhelpful, but potentially harmful, leading to long-lasting changes in brain function and eating behavior.
While this research was done in mice, it opens the door to further studies in humans. If future research confirms these findings, doctors may one day treat eating problems related to dieting by also focusing on improving gut health—not just calorie counting or willpower.
For now, the message is clear: repeated dieting can do more harm than good, and the tiny organisms in our gut may be a bigger part of the story than we thought.
If you care about gut health, please read studies about how probiotics can protect gut health, and Mycoprotein in diet may reduce risk of bowel cancer and improve gut health.
For more health information, please see recent studies about how food additives could affect gut health, and the best foods for gut health.
The research findings can be found in Advanced Science.
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