Recent findings in basic scientific research such as neurobiological and neuroimaging studies have suggested common pathways for food as well as drug intake. It was hypothesized that both compete for the same brain reward sites and that a higher BMI may be associated with lower substance use. The aim of this study was to investigate the relationship between body mass index (BMI) and substance use in a large sample of young male adults.

The sample consisted of 1,902 18-year-old males of a province of Austria in a naturalistic cross-sectional setting.

Questionnaires were administered to assess alcohol dependence (CAGE) and nicotine dependence (HSI). Urine samples were collected to assess the prevalence of recent illicit drug use. Associations between BMI and substance use were calculated by means of logistic regression analyses.

An inverse relationship between BMI and illicit substance use was found. This relationship remained significant after adjusting for possible confounding factors such as level of education, nicotine dependence, breath carbon monoxide (CO) levels and alcohol abuse and dependence. No significant association was found between BMI and nicotine and alcohol dependence.

A higher BMI was associated with lower illicit drug use in our sample of young adult males. As BMI increases rates of illicit drug use decrease. These results provide further evidence for the hypothesis that food and drugs may compete for the same brain reward sites.