Background: The identification of process and treatment variables associated with successful weight loss could be a pivotal strategy to reduce attrition and improve effectiveness of dietary treatment in obesity and could help find new therapeutic strategies.
Objective: The aim of study is to identify the psychological predictors of weight loss in patients with obesity compliant to continuous treatment at medical centers.
Design: Longitudinal observation of a large cohort of obese subjects entering weight-loss programs in the years 2000-2002.
Subjects/setting: Five hundred obese patients who completed 12-month weight-loss treatment by Italian medical centers offering different programs (78.8% females; age 46.2+/-10.8 years; body mass index [BMI; calculated as kg/m(2)] 37.3+/-5.6).
Main outcome measured: Measurements were obtained at baseline and after a 12-month weight-loss program. Psychological distress, binge eating, body uneasiness, and attitude toward eating were evaluated by self-administered questionnaires (Symptom Check List-90, Binge Eating Scale, Body Uneasiness Test, and Eating Inventory [Dietary Restraint, Disinhibition, and Hunger]), together with BMI changes. Weight-loss expectations and primary motivation for seeking treatment (health or improving appearance) were also recorded.
Results: At follow-up, mean percent weight loss was similar in males and females. Both hierarchical regression and logistic regression analysis revealed that increased dietary restraint and decreased disinhibition were the only independent psychological predictors of BMI change after controlling for age, sex, and baseline BMI (5% weight loss at 12 months: Eating Inventory Restraint (odds ratio [OR]: 1.15; 95% confidence interval [CI]: 1.09 to 1.21) and Disinhibition (OR: 0.92; 95% CI: 0.85 to 0.99); 10% weight loss: Restraint (OR: 1.11; 95% CI: 1.06 to 1.16) and Disinhibition (OR: 0.91; 95% CI: 0.85 to 0.98). Adjustment for centers did not change the results.
Conclusion: Successful weight loss was associated with increased dietary restraint and reduced disinhibition in obese patients seeking weight-loss treatment in several medical centers throughout Italy.