One of the most widely studied risk factors for eating disorders is dieting. Numerous theorists have posited that dieting increases the risk for onset of binge eating, bulimia nervosa (BN) and anorexia nervosa (AN) (Polivy & Herman, 1985; Fairburn et al., 1986; Huon, 1996; Wilson, 2002).

Dieting is defined as intentional and sustained restriction of caloric intake for the purposes of weight loss or weight maintenance (Herman & Polivy, 1975; Laessle et al., 1989; Wadden et al., 2002; Wilson, 2002). For weight loss to occur, dieting must result in a negative energy balance, whereas weight maintenance necessitates a balance between caloric intake and caloric expenditure (Rosenbaum et al., 1997). For a detailed discussion of the physiology of weight maintenance see Mercer (Chapter 2, this volume). Although this definition is straightforward, dieting is heterogeneous because different people engage in different behaviours to achieve weight loss or weight maintenance. Research suggests that 60–75% of adolescent dieters combine reduced caloric intake with increased physical activity, but a minority reports questionable weight control behaviours, such as meal skipping, and a smaller minority reports unhealthy behaviours such as fasting, vomiting or laxative abuse for weight control purposes (Emmons, 1992; Serdula et al., 1993; French et al., 1995). For example, one study of a large community recruited sample of adolescent females found that 4% reported vomiting, 5% reported diet pill use, 3% reported appetite suppressant use, 2% reported laxative use and 1% reported diuretic use (French et al., 1995).