The goal of the dietary intervention was to produce and maintain an average weight loss of 5% during the 18-month intervention period. The weight loss goal was based on results of the Trial of Nonpharmacologic Interventions in the Elderly (37), in which obese, hypertensive, older adults were able to maintain a 5.4% decrease in body weight over 2.5 years.
The dietary intervention was based on principles from the group dynamics literature (38) and social cognitive theory (39) and was divided into 3 phases: intensive (months 1–4), transition (months 5–6), and maintenance (months 7–18). The major emphasis of the intensive phase was to heighten awareness of the importance of and need for changing eating habits in order to lower calorie intake. Behavior change was facilitated using self-regulatory skills. These skills included self-monitoring, goal setting, cognitive restructuring, problem solving, and environmental management. One introductory individual session was followed by 16 weekly sessions (3 group sessions and 1 individual session each month). Each group session included problem solving, the review of a specific topic, and tasting of several well-balanced, low-fat, nutritious foods prepared with widely available ingredients. The individual sessions were used to review individual progress, solve problems, answer questions, and set goals. Body weight was measured weekly in both the diet-only and diet plus exercise groups and was recorded to the nearest 0.05 kg.
The transition phase included sessions every other week for 8 weeks (3 group sessions and 1 individual session). The goals for this phase included assisting participants who had not reached their weight loss goals in establishing new goals, and maintaining and preventing relapse in those participants who had reached their weight loss goals. The maintenance phase included monthly meetings and phone contacts, alternated every 2 weeks. Additionally, newsletters that provided pertinent nutritional information and notice of upcoming meetings were mailed at regular intervals. The goals of the maintenance phase included assisting participants who had reached their weight loss goals to maintain this weight loss, and providing counseling for participants who had a difficult time losing weight and adhering to the intervention. Adherence to the intervention was based on attendance at scheduled sessions and completion of the monthly assessment of weight.