Translational Psychiatry: “Fluctuating” brain signals linked to excess weight

Overeating and excess weight may be linked not so much to a strong desire for food as to inconsistency and “fluctuations” in the brain’s reward system. The greater the variation in the brain’s response to food from one instance to another, the more erratic eating behavior was and the higher a person’s body weight. The study was published in the journal Translational Psychiatry.

Researchers from the University of Tübingen studied 79 women: 35 with binge-eating disorder, 21 with a milder form of the condition, and 23 in a control group. Using brain scans, they measured how activity in the nucleus accumbens — a key reward center — changed from one trial to the next.

The researchers found that the greater the variation in this activity from one trial to another, the higher the participants’ body mass index. Among women with binge-eating disorder, ratings of how strongly they wanted a particular food fluctuated especially widely, particularly in situations involving uncertainty. The fluctuations affected specifically the brain regions involved in reward and cognitive control, rather than other areas.

Notably, the same instability was not observed during a money-based game, suggesting that the effect was specific to food. This could change how overeating is understood: the problem may not be that a person constantly experiences an intense desire to eat, but rather that their “signaling system” operates in an unstable and unpredictable way.

Understanding this mechanism could help researchers develop new approaches to treating eating disorders — not by suppressing food cravings altogether, but by making the brain’s response more stable. However, the study had a small sample size and included only women.

Binge-eating disorder is one of the most common eating disorders and is characterized by recurrent episodes of losing control over eating. It is often attributed to a lack of willpower or a strong craving for “tasty” foods, but a growing body of evidence points to differences in brain function. Viewing binge eating as a problem of response instability, rather than simply the strength of desire, could potentially lead to new approaches to treatment.