Socioeconomic gradient in body size and obesity among women: the role of dietary restraint, disinhibition and hunger in the Whitehall II study

OBJECTIVE: To examine the associations between three psychological eating behaviour variables-restraint, hunger and disinhibition-and body weight and size, and to assess their explanatory power for the employment grade gradients in body measurement. DESIGN: Cross-sectional analysis of self-report and clinical data. SUBJECTS: In all, 1470 women (aged 45-68 y, mean 56.3, s.d. 6.0 y), body mass index (BMI) 26.3 (4.8) kg/m(2) at phase 5 (1997-98) of the Whitehall II study. MEASUREMENTS: Employment grade was measured in six bands ranging from clerical (lowest) to administrative (highest). Five measures of body size were examined: BMI, weight in kilograms, waist and hip measurement in centimetres and waist-hip ratio. The eating behaviour variables were measured using Stunkard and Messick's (1985) Three-Factor Eating Questionnaire (TFEQ). RESULTS: Disinhibition and hunger scores were strongly and directly associated with all measures of body weight and size. Restraint score was not directly associated with body size and weight. An interaction between restraint and disinhibition scores was found. The low-restraint-high-disinhibition group (based on median score splits) were the heaviest (BMI 28.5 kg/m(2)) and largest (waist 85.8 cm), while the low-restraint-low-disinhibition group were the lightest (BMI 24.2 kg/m(2)) and smallest (waist 76.3 cm). Employment grade gradients in body weight and size remained largely unchanged after adjustment for dietary restraint. Moderate attenuations were found for disinhibition scores (3.6-15.0%) and hunger (4.8-19.9%) on the five body-size measures. CONCLUSION: Among middle-aged women high scores on hunger and disinhibition, as measured by the TFEQ, are associated with greater body size. Restraint relates to body size through its interaction with disinhibition. Individuals with high disinhibition and any level of restraint are heavier and larger than those with low levels of disinhibition. High disinhibition coupled with low levels of restraint is associated with the greatest weight and size. Hunger and disinhibition explain a moderate amount of the gradient in body size across employment grade and may be useful concepts for future work on the socioeconomic gradient in obesity and overweight.