Objective: To examine strategies-behavioral therapies, exercise, diet, anorectic drugs, surgery, or a combination of strategies-used for promoting weight loss in people with type II diabetes.
Research design and methods: Meta-analysis was used to synthesize research of promoting weight loss in the population. Literature search strategies involved reviewing bibliographies, conducting computer searches and surveys of relevant master's degree programs, and contacting representatives of the Centers for Disease Control. The final sample consisted of 89 studies involving 1,800 subjects. Data were extracted on 80 variables characterizing the sample of studies/subjects and on 23 outcome variables, including weight, metabolic control, lipids, and other physiological parameters.
Results: Diet alone had the largest statistically significant impact on weight loss (-20 lb) and metabolic control (-2.7% in glycosylated hemoglobin). All diets significantly improved fasting blood sugar. Behavioral programs alone had a statistically significant impact on weight loss (-6.4 lb) and metabolic control (-1.5%) but effects were less than for diet alone. Data from the few exercise studies indicated that weighted average effects for exercise on weight loss (-3.4 lb) and metabolic control (-0.8%) were less than diet alone. Behavioral therapy plus diet plus exercise was associated with statistically significant effect size estimates for weight loss (-8.5 lb) and metabolic control (-1.6%). Diet alone achieved better results. Effects of weight promotion strategies, in general, were smaller in experimental studies and for individuals over age 55.
Conclusions: Dietary strategies are most effective for promoting short-term weight loss in type II diabetes. A number of gaps exist in the extant literature- descriptions of subjects, interventions, or longitudinal outcomes beyond 12 months after intervention.