Food Reinforcement, the Dopamine D ₂ Receptor Genotype, and Energy Intake in Obese and Nonobese Humans

The authors measured food reinforcement, polymorphisms of the dopamine D ₂ receptor (DRD ₂) and dopamine transporter (DAT1) genes, and laboratory energy intake in 29 obese and 45 nonobese humans 18-40 years old. Food reinforcement was greater in obese than in nonobese individuals, especially in obese individuals with the TaqI A1 allele. Energy intake was greater for individuals high in food reinforcement and greatest in those high in food reinforcement with the TaqI A1 allele. No effect of the DAT1 genotype was observed. These data show that individual differences in food reinforcement may be important for obesity and that the DRD ₂ genotype may interact with food reinforcement to influence energy intake.