Objective: The objective of this study was to assess the relationship between the night eating syndrome (NES), measures of depression and self-esteem, test meal intake, and weight loss in obese participants.
Research methods and procedures: The study included 76 overweight (body mass index = 36.7 +/- 6.5 SD) outpatients (53 women and 23 men; aged 43.5 +/- 9.5 years) entering a weight loss program. They completed a Night Eating Questionnaire, the Zung Depression Inventory, and the Rosenberg Self-Esteem SCALE: Based on criteria by Stunkard et al. (Stunkard A, Berkowitz R, Wadden T, Tanrikut C, Reiss E, Young L. Binge eating disorder and the night eating syndrome. Int J Obes Relat Metab DISORD: 1996;20:1-6), participants had NES if they reported: (1) skipping breakfast > or =4 d/wk, interpreted as morning anorexia; (2) consuming more than 50% of total daily calories after 7 PM; and (3) difficulty falling asleep or staying asleep > or =4 d/wk. Eleven (14%) participants met the criteria for NES. After an 8-hour fast, all participants ingested a nutritionally complete liquid meal through a straw from a large opaque cooler until extremely full. They also completed ratings of hunger and fullness before and after this meal.
Results: Night eaters had higher depression (p = 0.04), lower self-esteem (p = 0.003), and less hunger (p = 0.005), and a trend for more fullness (p = 0.06) before the daytime test meal than the others. However, there were no significant differences in test-meal intake between groups. Nevertheless, test-meal intake was greater later in the day only for the night eaters (p = 0.01). Over a 1-month period, the night eaters lost less weight (4.4 +/- 3.2 kg) than the others (7.3 +/- 3.2 kg; p = 0.04), after controlling for body mass index.
Discussion: NES is a syndrome with distinct psychopathology and increased food intake later in the day, both of which may contribute to poorer weight loss outcome. NES criteria need to be better quantified and NES deserves consideration as a diagnostic eating disorder.