Few Commercial Diets Show Evidence of Sustained Weight Loss

Last year, the market for commercial weight-loss programs was dominated by Weight Watchers (45%), Nutrisystem (14%), and Jenny Craig (13%). In this systematic review, researchers evaluated 45 studies (including 39 randomized trials of ≥12 weeks' duration) in which commercial weight-loss programs were compared with control interventions (e.g., printed materials only, sessions with a health professional, behavioral counseling) or no intervention.

Weight loss for commercial programs (relative to controls) was as follows:

• Weight Watchers, ≥2.6% greater at 12 months

• Jenny Craig, ≥4.9% greater at 12 months

• Nutrisystem, ≥3.8% greater at 3 months (no trials continued to 12 months)

• Atkins, 1% to 2.9% greater at 12 months

• Very-low-calorie programs (i.e., H…