Weight Loss During the Intensive Intervention Phase of the Weight-Loss Maintenance Trial

Background

To improve methods for long-term weight management, the Weight Loss Maintenance (WLM) trial, a four-center randomized trial, was conducted to compare alternative strategies for maintaining weight loss over a 30-month period. This paper describes methods and results for the initial 6-month weight-loss program (Phase I).

Methods

Eligible adults were aged ≥25, overweight or obese (BMI=25–45 kg/m²), and on medications for hypertension and/or dyslipidemia. Anthropomorphic, demographic, and psychosocial measures were collected at baseline and 6 months. Participants (n=1685) attended 20 weekly group sessions to encourage calorie restriction, moderate-intensity physical activity, and the DASH (dietary approaches to stop hypertension) dietary pattern. Weight-loss predictors with missing data were replaced by multiple imputation.

Results

Participants were 44% African American and 67% women; 79% were obese (BMI≥30), 87% were taking anti-hypertensive medications, and 38% were taking antidyslipidemia medications. Participants attended an average of 72% of 20 group sessions. They self-reported 117 minutes of moderate-intensity physical activity per week, kept 3.7 daily food records per week, and consumed 2.9 servings of fruits and vegetables per day. The Phase-I follow-up rate was 92%. Mean (SD) weight change was −5.8 kg (4.4), and 69% lost at least 4 kg. All race–gender subgroups lost substantial weight: African-American men (−5.4 kg ± 7.7); African-American women (−4.1 kg ± 2.9); non–African-American men (−8.5 kg ± 12.9); and non–African-American women (−5.8 kg ± 6.1). Behavioral measures (e.g., diet records and physical activity) accounted for most of the weight-loss variation, although the association between behavioral measures and weight loss differed by race and gender groups.

Conclusions

The WLM behavioral intervention successfully achieved clinically significant short-term weight loss in a diverse population of high-risk patients.