Real-World Twelve-Month Weight Loss Outcomes in a Comprehensive Obesity Care Program Utilizing Individualized Nutrition Therapy and Incretin-Based Obesity Medications

Background/Objectives: Incretin-based obesity medications (IOMs) produce substantial weight loss, but the added benefit of structured nutritional therapy remains unclear. We compared 12-month weight loss between individualized carbohydrate-reduced nutritional therapy combined with IOMs (VINT+IOM) and IOM-based care without structured nutritional therapy (IOM only). Methods: In this retrospective cohort study, we analyzed 4,269 adults enrolled in a telemedicine obesity care program (VINT+IOM, n = 1,658; IOM only, n = 2,611). Both pathways included clinician-guided medication management and behavioral coaching. The primary analysis included GLP-1-naive participants taking a single agent (semaglutide or tirzepatide). Adjusted weight change was estimated using longitudinal linear mixed-effects models. Results: Retention at 12 months was 77% in the VINT+IOM group and 72% in the IOM-only group. Among GLP-1-naive semaglutide users, adjusted 12-month weight loss was greater with VINT+IOM than with IOM only (13.9 vs. 10.9 kg; difference 3.0 kg, 95% CI 0.6 to 5.4; P = 0.012), and observed percentage weight loss was 13.3% vs. 11.1%. Among tirzepatide users, adjusted weight loss was 20.8 vs. 15.6 kg (difference 5.2 kg, 95% CI 1.8 to 8.7; P = 0.003), and observed percentage weight loss was 19.7% vs. 15.6%. Responder rates also favored VINT+IOM. In the overall cohort, adjusted weight loss was 13.3 vs. 9.8 kg (P < 0.001), and the advantage persisted among participants with prior GLP-1 exposure. Weight loss continued between 6 and 12 months in both groups. Approximately 80% of participants in each pathway had an IOM proportion of days covered of 80% or higher. Self-reported side effects were similar (63.6% vs. 64.6%). Conclusions: In this real-world cohort, adding individualized carbohydrate-reduced nutritional therapy to IOM-based care was associated with greater 12-month weight loss than IOM-based care without structured nutritional therapy. These findings support further evaluation of individualized nutrition as an adjunct to incretin-based pharmacotherapy, ideally in randomized trials.