In this study, alterations in objectively measured physical activity (PA) were shown to be inversely associated with changes in body weight, body composition, and fat distribution in response to weight-loss diets, and such associations were more evident in persons with high-fat or average-protein diet than low-fat or high-protein diet.

• In 535 participants with overweight/ obesity randomized to 4 weight-loss diets differing in macronutrients, PA was recorded objectively with pedometers, and body composition and fat distribution were assessed at baseline, 6 months, and 24 months.

• From baseline to 6 months, when the maximum weight loss occurred, each 1000 daily steps increase in PA was found to be linked with a greater decrease in body weight and waist circumference.

• For changes in body composition and fat distribution, similar inverse links were observed.

• Across the 24-months intervention span, trajectory of the above adiposity measures varied between the patterns of PA alteration.

• Weight loss was maintained from 6 months to 24 months in participants with the largest increase in PA, while weight regaining was evident in participants with less increment in PA.

• Dietary fat or protein consumption significantly altered the links between alterations in PA and changes in body weight and waist circumference over 24 months.