Mediators of Weight Loss and Weight Loss Maintenance in Middle‐aged Women

<jats:p>Long‐term behavioral self‐regulation is the hallmark of successful weight control. We tested mediators of weight loss and weight loss maintenance in middle‐aged women who participated in a randomized controlled 12‐month weight management intervention. Overweight and obese women (<jats:italic>N</jats:italic> = 225, BMI = 31.3 ± 4.1 kg/m<jats:sup>2</jats:sup>) were randomly assigned to a control or a 1‐year group intervention designed to promote autonomous self‐regulation of body weight. Key exercise, eating behavior, and body image variables were assessed before and after the program, and tested as mediators of weight loss (12 months, 86% retention) and weight loss maintenance (24 months, 81% retention). Multiple mediation was employed and an intention‐to‐treat analysis conducted. Treatment effects were observed for all putative mediators (Effect size: 0.32–0.79, <jats:italic>P</jats:italic> < 0.01 vs. controls). Weight change was −7.3 ± 5.9% (12‐month) and −5.5 ± 5.0% (24‐month) in the intervention group and −1.7 ± 5.0% and −2.2 ± 7.5% in controls. Change in most psychosocial variables was associated with 12‐month weight change, but only flexible cognitive restraint (<jats:italic>P</jats:italic> < 0.01), disinhibition (<jats:italic>P</jats:italic> < 0.05), exercise self‐efficacy (<jats:italic>P</jats:italic> < 0.001), exercise intrinsic motivation (<jats:italic>P</jats:italic> < 0.01), and body dissatisfaction (<jats:italic>P</jats:italic> < 0.05) predicted 24‐month weight change. Lower emotional eating, increased flexible cognitive restraint, and fewer exercise barriers mediated 12‐month weight loss (<jats:italic>R</jats:italic><jats:sup>2</jats:sup> = 0.31, <jats:italic>P</jats:italic> < 0.001; effect ratio: 0.37), but only flexible restraint and exercise self‐efficacy mediated 24‐month weight loss (<jats:italic>R</jats:italic><jats:sup>2</jats:sup> = 0.17, <jats:italic>P</jats:italic> < 0.001; effect ratio: 0.89). This is the first study to evaluate self‐regulation mediators of weight loss and 2‐year weight loss maintenance, in a large sample of overweight women. Results show that lowering emotional eating and adopting a flexible dietary restraint pattern are critical for sustained weight loss. For long‐term success, interventions must also be effective in promoting exercise intrinsic motivation and self‐efficacy.</jats:p>