Do Brains of Obese Individuals Respond Differently to Food?

Reader of these pages are by now probably quite familiar with the complexity of ingestive behaviour and the importance of understanding brain function in relationship to food intake.

A study, published in this month’s issue of Obesity, illustrates how differences in brain function between obese and non-obese people can explain important differences in response to food.

In this study, Laura Martin and colleagues from the Kansas Medical Center, used functional magnetic resonance imaging (fMRI) to examine changes in brain activity in obese and normal weight adults while they viewed food and nonfood images in premeal and postmeal states.

Both in the premeal and postmeal state, obese participants showed showed increased activation in the anterior cingulate cortex (ACC) and the medial prefrontal cortex (MPFC), regions of the brain responsible for the reward response and impulsiveness, respectively.

In addition, activation of the ACC was associated with decreased levels of self-reported disinhibition while MPFC activation was associated with increased self-reported hunger amongst obese participants.

These findings clearly suggest that brain function associated with food motivation differs in obese and non-obese adults and may well explain the different susceptibilities to weight gain and variability in response to diet interventions.

Given the emerging science on brain plasticity, it is certainly of interest whether or not these differences in brain function are acquired or are indeed innate. Whatever the case, we need to understand and acknowledge that our brains respond differently to the same food stimuli which easily explains why some people may find it much harder to resist overeating in our current obesogenic environment than others.

As I have said before, the obesity epidemic is simply the natural response to our unnatural environment.

Edmonton, Alberta