Effectiveness of a digital weight management program on diet quality: a randomized controlled trial

Background: The effect of behavioral commercial weight programs (CP) on weight loss is clear, yet their effects on diet quality are less studied. Objectives: This study aims to evaluate the relative effectiveness of a digital CP on diet quality compared with standard nutritional guidance (SNG) over 6 months. Methods: This randomized controlled trial (clinicaltrials.gov/NCT05648344) included 376 United States adults with a body mass index of 27–45 kg/m² and a self-reported desire to lose weight. Participants were randomly assigned to a 6-month digital, behavioral CP (WeightWatchers) (n = 187) or to SNG (n = 189). SNG participants received a monthly email with information from the United States Department of Agriculture MyPlate.gov. The primary outcome was the between-group, 6-month difference in diet quality (Healthy-Eating Index, HEI-2020) calculated from 3 24-h dietary recalls gathered with the Automated Self-Administered 24-h Dietary Assessment Tool. Secondary outcomes included percent weight loss and weight-loss milestones of 3%, 5%, and 10%. Intention-to-treat, 6-month differences between CP and SNG were compared with analysis of covariance or logistic regressions with multiple imputation adjusted for sex, age, race, ethnicity, education, and baseline values. Results: Participant's mean age was 47.7 years (standard deviation = 12); 65.7% self-identified as non-Hispanic White, 20.7% as male, and 17.8% experienced food insecurity. Improvements in mean HEI were significantly greater with CP, 5.3 (standard error = 1.5), than SNG, 1.1 (1.4); between-group mean difference 4.2 (1.2); 95% confidence interval (CI): 1.8, 6.6. CP participants lost significantly more % body weight, –5.4% (0.9), than SNG participants, –1.5% (0.8); mean difference –3.9% (0.7); 95% CI: –5.4, –2.5. Odds ratios for achieving 3%, 5%, and 10% weight loss for CP compared with SNG participants were 2.7 (95% CI: 1.7, 4.2), 3.3 (95% CI: 2.1, 5.4), and 7.1 (95% CI: 3.2, 15.8), respectively. Conclusions: A CP was significantly more effective than SNG for improving diet quality and weight loss among a diverse sample of adults living with overweight or obesity in the United States. Trial registration number: https://clinicaltrials.gov/study/NCT05648344.