Appetite 48 (2007) 12–19 Research report From motivation to behaviour: A model of reward sensitivity, overeating, and food preferences in the risk profile for obesity Caroline Davis a,b,c,Ã , Karen Patte a , Robert Levitan c , Caroline Reid a , Stacey Tweed b , Claire Curtis a a Department of Kinesiology & Health Sciences, York University, Toronto, Canada b Graduate Programme in Psychology, York University, Toronto, Canada c Centre for Addiction and Mental Health, Toronto, Canada Received 30 March 2006; received in revised form 18 May 2006; accepted 23 May 2006 Abstract The reinforcing effects of addictive drugs and palatable foods are regulated, at least in part, by a common biological mechanism. The reactivity or sensitivity of these brain reward regions have been found to correlate significantly with the risk for a variety of drug addictions. Sensitivity to Reward (STR) is conceptualised as a psycho-biological personality trait rooted firmly in the availability of dopamine in the mesocorticolimbic (‘common reward’) pathways, and as such is a good candidate for studying motivational factors and eating behaviours. The purpose of the present study was to examine whether STR was related to behaviours that contribute to excess body weight. Structural equation modelling procedures were used with a sample of healthy adult women (n ¼ 151). We hypothesised that STR would positively predict overeating and a preference for foods high in fat and sugar; and that these two behaviour would, in turn, predict a higher Body Mass Index. Results provided an excellent fit of the model to our data confirming our view that a personality trait like STR can only influence a physical condition like body weight indirectly by the way it co-varies with behaviours that contribute directly to variation in the outcome variable. r 2006 Elsevier Ltd. All rights reserved. Keywords: Sensitivity to reward; Overeating; Food preferences; BMI Introduction The reinforcing effects of addictive drugs and palatable foods are regulated, at least in part, by a common brain mechanism depending crucially on the level of dopamine (DA) activation in mesocorticolimbic regions (e.g. Di Chiara et al., 2004; Risinger, Freeman, Rubinstein, Low, & Grandy, 2000). Indeed, the sub-cortical brain does not seem to differentiate among rewards provoked by natural reinforcers like food, illicit drugs like cocaine, or beha- viours like gambling (Kelley, Schiltz, & Landry, 2005). For example, two recent studies found that obese women had lower rates of alcohol (Kleiner et al., 2004) and marijuana use (Warren, Frost-Pineda, & Gold, 2005) than their normal weight, age-matched counterparts, and that, in both cases, an inverse relationship existed between body mass index (BMI) and drug use. The authors concluded that overeating competes with pharmacologic agents for brain reward sites, and thereby may serve as a buffer for the use and abuse of other addictive behaviours. Com- plementary to this viewpoint is evidence that appetite suppression is a major pharmacological effect of chronic drug use (see Cochrane, Malcolm, & Brewerton, 1998). Clearly many factors influence the kinds of pleasure we pursue in our daily lives. The context—through classical and operant conditioning processes—is particularly im- portant in determining the choices we make and the frequency of their use (Corwin & Hajnal, 2005). In most Western societies, the convenience, the availability, and the ARTICLE IN PRESS www.elsevier.com/locate/appet 0195-6663/$ - see front matter r 2006 Elsevier Ltd. All rights reserved. doi:10.1016/j.appet.2006.05.016 Ã Corresponding author. 343 Bethune College, 4700 Keele Street, Toronto, Ontario, Canada, M3J 1P3. Tel.: +1 416 736 2100; fax: +1 416 736 5774. E-mail address: cdavis@yorku.ca (C. Davis).