This paper reports the final 24-month outcomes of a randomized controlled trial evaluating the effect of additional therapeutic contact (ATC) as an adjunct to a community-based weight-management program for overweight and obese 13-16-year-olds. ATC involved telephone coaching or short-message-service and/or email communication once per fortnight. Adolescents were randomized to receive the Loozit group program-a two-phase behavioral lifestyle intervention with (n=73), or without (n=78), ATC in Phase 2. Adolescents/parents separately attended seven weekly group sessions (Phase 1), followed by quarterly adolescent sessions (Phase 2). Assessor-blinded, 24-month changes in anthropometry and metabolic health included primary outcomes body mass index (BMI) z-score and waist:height ratio (WHtR). Secondary outcomes were self-reported psychosocial and lifestyle changes. By 24 months, 17 adolescents had formally withdrawn. Relative to the Loozit program alone, ATC largely had no impact on outcomes. Secondary pre-post assessment of the Loozit group program showed mean (95% CI) reductions in BMI z-score (-0.13 (-0.20, -0.06)) and WHtR (-0.02 (-0.03, -0.01)) in both arms, with several metabolic and psychosocial improvements. Adjunctive ATC did not provide further benefits to the Loozit group program. We recommend that further work is needed to optimize technological support for adolescents in weight-loss maintenance. Australian New Zealand Clinical Trials Registry Number ACTRNO12606000175572.