Brain imaging studies suggest that individuals with decreased dopamine output find eating less pleasurable, and are more likely to be obese or to more susceptible to weight gain.

Dopamine is the neurotransmitter that plays a major role in the reward and pleasure pathways in the brain. Eating is associated with dopamine release and the degree of pleasure from eating is related to the amount of dopamine released.

Evidence shows that obese individuals have fewer dopamine (D2) receptors in the brain, and because they experience less pleasure when eating, they have to eat more to compensate.

Using Functional Magnetic Resonance Imaging (fMRI), the researchers measured a dopamine rich region of the brain called the dorsal striatum. The imaging indicated activity in the region in response to tasting a chocolate milkshake, and no response to a tasteless solution. The dorsal striatum region of the brain was less active in obese individuals than in lean individuals.

The researchers also tracked participants’ changes in body mass index (BMI) over a 1-year follow up. Results showed that those participants with decreased dorsal striatum activity in response to tasting the milkshake were more likely to gain weight.

The results suggest that individuals with decreased dopamine output who are at increased risk for unhealthy weight gain may be able to correct this deficit through behavioral interventions, helping to prevent and treat obesity.
References:
1. Eric Stice, et al. Blunted activation of brain reward circuitry increases risk for future weight gain. Oregon Research Institute. October 2008.
2. Image by kimchii