Despite proven efficacy, there are few published evaluations of telephone-delivered interventions targeting physical activity, healthy eating, and weight loss in community dissemination contexts. This study aims to evaluate participant and program outcomes from the Optimal Health Program, a telephone-delivered healthy lifestyle and weight loss program provided by a primary health care organization. Dissemination study used a single-group, repeated measures design; outcomes were assessed at 6-month (mid-program; n = 166) and 12-month (end of program; n = 88) using paired analyses. The program reached a representative sample of at-risk, primary care patients, with 56 % withdrawing before program completion. Among completers, a statistically significant improvement between baseline and end of program was observed for weight [mean change (SE) -5.4 (7.0) kg] and waist circumference [-4.8 (9.7) cm], underpinned by significant physical activity and dietary change. Findings suggest that telephone-delivered weight loss and healthy lifestyle programs can provide an effective model for use in primary care settings, but participant retention remains a challenge.