Although scientists have long speculated, and evidence increasingly shows, that similar brain mechanisms underlie addictions to alcohol, drugs, and nicotine and excessive food intake (Grigson, 2002; Simansky, 2005; Volkow & Wise, 2005), only a handful of studies have looked at associations between overweight and obesity and various substance use disorders. Negative associations between substance use disorders and overweight and/or obesity would support the hypothesis that compulsive overeating and compulsive use of substances compete for the same reward systems in the brain. Our results do not provide consistently strong support for this hypothesis. Our findings suggest that excessive and dysfunctional substance use can co-occur with overweight and obesity, and in some cases the risk for substance use disorders is elevated among individuals with higher BMI. It therefore appears that many individuals with substance use disorders are sensitive to the rewarding properties of both psychoactive substances and food. Gender differences in relationships between BMI and substance use disorders require further investigation. For instance, although prior research indicates that women who drink alcohol consume fewer calories from other sources (Colditz et al., 1991), it is not clear why alcohol calories replace food calories among women but not men.
