Efficacy of commercial weight-loss programs: an updated systematic review

Abstract

Background: Commercial and proprietary weight-loss programs are popular obesity treatment options, but their efficacy is unclear.

Purpose: To compare weight loss, adherence, and harms of commercial or proprietary weight-loss programs versus control/education (no intervention, printed materials only, health education curriculum, or <3 sessions with a provider) or behavioral counseling among overweight and obese adults.

Data sources: MEDLINE and the Cochrane Database of Systematic Reviews from inception to November 2014; references identified by program staff.

Study selection: Randomized, controlled trials (RCTs) of at least 12 weeks' duration; prospective case series of at least 12 months' duration (harms only).

Data extraction: Two reviewers extracted information on study design, population characteristics, interventions, and mean percentage of weight change and assessed risk of bias.

Data synthesis: We included 45 studies, 39 of which were RCTs. At 12 months, Weight Watchers participants achieved at least 2.6% greater weight loss than those assigned to control/education. Jenny Craig resulted in at least 4.9% greater weight loss at 12 months than control/education and counseling. Nutrisystem resulted in at least 3.8% greater weight loss at 3 months than control/education and counseling. Very-low-calorie programs (Health Management Resources, Medifast, and OPTIFAST) resulted in at least 4.0% greater short-term weight loss than counseling, but some attenuation of effect occurred beyond 6 months when reported. Atkins resulted in 0.1% to 2.9% greater weight loss at 12 months than counseling. Results for SlimFast were mixed. We found limited evidence to evaluate adherence or harms for all programs and weight outcomes for other commercial programs.

Limitation: Many trials were short (<12 months), had high attrition, and lacked blinding.

Conclusion: Clinicians could consider referring overweight or obese patients to Weight Watchers or Jenny Craig. Other popular programs, such as Nutrisystem, show promising weight-loss results; however, additional studies evaluating long-term outcomes are needed.

Primary funding source: None. (

Prospero: CRD4201-4007155).

Figure 1

Difference in mean percent weight change between commercial programs that dominate the market share (Weight Watchers; Jenny Craig; Nutrisystem) and comparators displayed by time point. Diamond size is standardized across trials and does not reflect sample size analyzed. Attrition reflects the percentage of participants unavailable for weight measurement at that time point in the trial. *Results from completers’ analysis. **Results reported in more than one article. Abbreviations: C – attrition reported in comparator arm at time point; DM – overweight or obese patients with diabetes mellitus; GEN – general population of patients with overweight and obesity; LC – low carbohydrate version of program; NR – not reported; P – attrition reported in commercial program arm at time point; T – telephone based program; WW – Weight Watchers.

Figure 2

Difference in mean percent weight change between commercial programs that use very-low-calorie or low calorie meal replacements (HMR; Medifast; Optifast) and comparators displayed by time point. Diamond size is standardized across trials and does not reflect sample size analyzed. Attrition reflects the percentage of participants unavailable for weight measurement at that time point in the trial. *Results from completers’ analysis. **Trial reported median percent difference in weight change rather than mean. ***Intervention was low-calorie (1200 to 1500 calories daily) during weight loss phase. Abbreviations: C – attrition reported in comparator arm at time point; DM – overweight or obese patients with diabetes mellitus; GEN – general population of patients with overweight and obesity; HMR – Health Management Resources; NR – not reported; P – attrition reported in commercial program arm at time point; T – telephone based program.

Figure 3

Difference in mean percent weight change between self-directed commercial programs (Atkins; Biggest Loser Club; eDiets; Lose It!, SlimFast) and comparators displayed by time point. Diamond size is standardized across trials and does not reflect sample size analyzed. Attrition reflects the percentage of participants unavailable for weight measurement at that time point in the trial. Panel C displays the results for. *Results from completers’ analysis. **Results reported in more than one article. ***Value represents overall attrition at time point. Abbreviations: C – attrition reported in comparator arm at time point; DM – overweight or obese patients with diabetes mellitus; GEN – general population of patients with overweight and obesity; NR – not reported; P – attrition reported in commercial program arm at time point.