In Reward Deficiency Syndrome, drugs are purported to stimulate the reward mechanisms in the brain so intensely that, to compensate, the amount of dopamine D2 receptors (DD2R) decreases. This results in a need for increased intake to experience the same degree of reward. Without the increased intake, people will experience cravings and withdrawal symptoms. A theory exists that food addiction decreases DD2R in a similar way as drugs of abuse. A meta-analysis was conducted to examine the association between body mass index (BMI) and the Taq1A polymorphism, given that the A1 allele is associated with a 30-40% lower number of DD2R and is a risk factor for drug addiction. The hypothesis stated that if a lower density of DD2R is indicative of physical addiction, then if food addiction occurs, those with the A1 allele should have a higher BMI. The meta-analysis compared those with the A1 allele (A1/A1 and A1/A2) to those without the A1 allele (A2/A2) and found no difference in BMI. The authors concluded that there was no support for a reward deficiency theory of food addiction. However, the authors noted that several reports exist showing that those with the A1 allele are less likely to benefit from a weight-loss intervention, which they attributed to a reflection of increased impulsivity.View article