Why Do Most Restrained Eaters Fail in Losing Weight?: Evidence from an fMRI Study

BACKGROUND: Restraint dieting is a key step in the avoidance of obesity and other eating problems, but why some restraint eaters (REs) succeed and some fail in dieting is unknown. The difference between successful REs (S-REs) and unsuccessful REs (US-REs) is still unknown. This is the first study to compare the fMRI reactivity among US-REs, S-REs and unrestrained eaters (UREs) in a food-related Go/NoGo paradigm. METHODS: Functional magnetic resonance imaging (fMRI) was used to examine the neural responses corresponding to the success of dieting in REs. Eighteen S-REs, 17 US-REs and 17 UREs were asked to perform a Go/No-Go task after being shown pictures of either high-caloric or low-caloric food. RESULTS: fMRI results revealed stronger activations for high-caloric food in areas associated with executive function and inhibition (i.e., middle frontal gyrus and cerebellum) among S-REs than among US-REs. In contrast, both US-REs and UREs showed stronger activations for low-caloric food in reward areas (i.e., orbitofrontal cortex (OFC)) than S-REs. CONCLUSION: Our results provide evidence that food temptations may trigger processes of successful inhibition control in S-REs, whereas US-REs may fail in resisting the attraction to high-caloric food, thereby showing a high probability of overeating.