Weight loss success linked with self-control regions of the brain.
Previous studies show that evidence on the effectiveness of weight management programs often comes from uncontrolled program evaluations. Sparse data exists as to which neurocognitive pathways regulate weight loss and control, with insufficient responses to diets being attributed to hormonal adaptations which override self-control of food intake. Two hormones, leptin and ghrelin, are known to trigger the body to eat in a weight-loss setting, with levels of these hormone changing rapidly when weight is shed. The current study uses functional MRI (fMRI) to identify a neural signature and assess the roles these hormones have in achieving weight loss.
The current study follows 24 subjects in a weight-loss program using fMRI to assess the lateral prefrontal cortex, which is linked with self-regulation, and the ventral medial prefrontal cortex, a brain area involved in motivation, desire, and value. Subjects were shown pictures of appetizing foods as well as control pictures of scenery. Results show that when participants are shown pictures of appetizing foods, the ventral medial prefrontal cortex area becomes more active on fMRI. Data findings show that at one month and three months, the signal from the ventral prefrontal cortex declines the most in people who lost the most weight; additionally, the lateral prefrontal cortex signal involved in self-control increased throughout the study.
Results show the self-control area increased its activity and the value area decreased its activity, with the amount of change predictive of successful weight loss. Data findings show that while all participants lost weight, those who achieved the greatest weight loss had fMRI levels indicating a better ability to self-control, and, at the end of the 3-month study, the hormones ghrelin and leptin were starting to return to baseline, suggesting that a new set point was achieved.
The team surmise that they show activation in prefrontal regions associated with self-control contributes to successful weight loss. For the future, the researchers state their results suggest that weight loss treatments which stimulate the prefrontal regions associated with self-control could contribute to successful weight loss and maintenance.