Macronutrient effects on food intake and satiety in binge eating disorder and bulimia nervosa

The eating disorders bulimia nervosa (BN) and binge eating disorder (BED) are characterized by recurrent episodes of binge eating, where the consumption of large amounts of food is accompanied by a feeling of loss of control over eating. The study of factors that control food intake and its termination may be important in understanding and effectively treating these disorders. In individuals without eating disorders, protein reduces later food intake to a greater extent than carbohydrate or fat. Similarly, higher proportions of dietary protein are correlated with lower total food intake. Patients with BN consume a smaller proportion of protein during binges and throughout the day than non-clinical controls. Intake of protein, which elicits the release of satiety agents glucagon and cholecystokinin (CCK) may help to prevent overconsumption. Therefore, supplementing the diet of BN and BED patients with protein was hypothesized to reduce their binge eating frequency and intake at an ad libitum test meal. Women with BN or BED (n = 18) kept detailed food records and ingested nutritional supplements (280 kcal) consisting of 76% protein or 96% carbohydrate, three times daily over two 2-week periods in a counterbalanced order. On the final morning of each 2-week period, participants were given a 420 kcal supplement of protein or carbohydrate in counterbalanced order and offered an ad libitum meal 3 hours later. During protein supplementation, binge eating episodes occurred less frequently than during carbohydrate supplementation (0.16/day vs. 0.42/day) and less frequently than during a baseline week of self-monitoring (0.43/day). A smaller increase in participants' body weight accompanied protein supplementation compared to carbohydrate supplementation (0.27 vs. 1.06 kg). Before test meals, participants reported less hunger and greater fullness on visual analogue scales after protein than after carbohydrate intake. Intake at test meals was lower after protein supplementation than after carbohydrate (673 vs. 856 kcal). Therefore, adding protein to the diets of BN and BED patients reduced binge eating and reduced intake at a test meal. This suggests that protein's satiating effect may be generalizable to patients with eating disorders and may help to reduce their binge eating, overall intake, and even associated weight gain.