Yo-yo dieting, characterized by cycles of severe restriction followed by rapid weight regain, is notoriously harmful. New research reveals another detrimental effect: it causes lasting alterations to gut bacteria, driving cravings for fatty and sugary foods and making sustained weight loss more difficult. A study led by France’s University of Rennes and Paris-Saclay, published in *Advanced Science*, observed this effect in mice. These findings could improve anti-obesity therapies and promote healthier eating, potentially by targeting specific gut microorganisms.
Researchers Véronique Douard (Paris-Saclay) and Gaëlle Boudry (Rennes) conducted experiments on mice, alternating a standard diet with a high-fat, high-sugar diet mimicking unhealthy Western eating patterns. A key observation was that the mice consistently overate, consuming junk food for pleasure rather than hunger when it became available again. The study authors traced this behavior to a long-term change in the gut microbiota. Crucially, when these altered bacteria were transferred to mice not subjected to the yo-yo dieting, they developed the same binge-eating tendency.
“We demonstrated that alternating between a high-energy diet and a standard diet durably reshapes the gut microbiota,” state the researchers, “towards a profile linked to increased pleasure-driven eating and weight gain.” The next research phase aims to understand the underlying mechanisms and determine if the same effects occur in humans.