Effectiveness of a protein-supplemented very-low-calorie diet program for weight loss: a randomized controlled trial in South Korea

Introduction Weight-loss strategies through meal replacements are effective and sustainable options. However, few studies have assessed their effects on weight loss including body composition through protein-supplemented meal replacements targeting the Asian population, including Koreans. This study aimed to assess the effectiveness and safety of a protein-supplemented very-low-calorie diet (PSVLCD) for weight reduction and changes in body composition in individuals with obesity over a 12-month long-term period.Methods In total, 106 participants with obesity were randomly assigned to a PSVLCD or control group (food-based calorie-restricted diet). Body weight, waist circumference, body composition, and blood marker levels were measured throughout the study. Statistical analyses were performed to compare outcomes between the groups.Results Among the 106 participants, 84 completed the 12-month follow-up. Intention-to-treat analysis showed that the mean weight loss from baseline to 12 months was -6.86 kg (8.21% of baseline weight) in the PSVLCD group and - 4.66 kg (5.47% of initial body weight) in the control group; the difference was -2.20 kg with a marginally significant interval (95% confidence interval [CI], -4.90; 0.50). Waist circumference (-8.35 cm vs. -4.85 cm; mean difference, -3.49 cm; 95% CI, -6.48 to -0.50) and visceral fat area (-28.28 cm2 vs. -13.26 cm2; mean difference, -15.03cm2; 95% CI, -29.01 to -1.04) also significantly decreased in the PSVLCD group at 12 months.Discussion The PSVLCD group demonstrated a substantial initial reduction in waist circumference that was sustained over the study period, alongside a marginally significant decrease in weight. These findings suggest that a protein-supplemented very-low-calorie diet may be an effective strategy for long-term weight management and body composition improvement in individuals with obesity.Clinical trial registration ClinicalTrials.gov, identififer NCT04597788.