15 overweight dogs were enrolled in a 3-month energy restriction protocol to help them reach an ideal body condition. Rate of weight loss was 1 to 1.5% of body weight loss per week. Dogs were fed a weight management diet fortified with key nutrients to support cardiac health (omega-3 fatty acid, taurine, L-carnitine) and assigned to a daily walk of moderate intensity (5 km/hour) for the 12-week study. At the end of the study all dogs reached an ideal body condition. DEXA measurement showed maintenance of lean tissue and a 60% reduction in initial body fat mass. Normalisation of heart rate was also observed: heart rate decreased by 17% both at rest and during the walk after only 6 weeks, illustrating a beneficial impact of both weight loss and exercise on cardiac function. Voluntary physical activity also increased by 1.5 hours per day following weight loss.