• Robert Ross, Amy E Latimer-Cheung, Andrew G Day, Andrea M Brennan, and James O Hill.
• School of Kinesiology and Health Studies (Ross, Latimer-Cheung) and Department of Medicine, Division of Endocrinology and Metabolism (Ross), Queen's University; Kingston Health Sciences Centre (Day), Kingston, Ont.; AdventHealth Orlando, Translational Research Institute (Brennan), Orlando, Fla.; University of Alabama at Birmingham, Department of Nutritional Sciences (Hill), Birmingham, Ala. rossr@queensu.ca.
• CMAJ. 2022 Mar 7; 194 (9): E324E331E324-E331.

BackgroundEfforts to manage obesity through weight loss are often unsuccessful as most adults are not able to sustain the major changes in behaviour that are required to maintain weight loss long term. We sought to determine whether small changes in physical activity and diet prevent weight gain in adults with overweight and obesity.MethodsWe randomized 320 sedentary adults with overweight or obesity to monitoring alone (MA, n = 160) or a small change approach (SCA, n = 160). In Phase I (2 yr), MA participants were asked to maintain their normal lifestyle and SCA participants were counselled to make small changes in diet and physical activity, namely a suggested increase in daily step count of 2000 steps with a decrease in energy intake of 100 kcal per day, with group and individual support. Phase II (1 yr) was a passive follow-up period. The difference in change in body weight between groups at 24 and 36 months from baseline was the primary outcome. Additional outcomes included waist circumference and cardiorespiratory fitness.ResultsOverall, 268 participants (83.8%) completed the 2-year intervention, and 239 (74.7%) returned at the end of the follow-up period at 3 years. The difference in body weight change between the SCA and MA groups was significant at 3, 6, 12 and 15 months from baseline, but was no longer significant at 24 months (mean change 0.9 [standard error (SE) 0.5] kg v. -0.4 [SE 0.5] kg; difference -0.6, 95% confidence interval [CI] -1.9 to 0.8) or at 36 months (-1.2 [SE 0.8] v. -0.7 [SE 0.8] kg; difference -0.5, 95% CI -2.2 to 1.2). Changes in waist circumference and cardiorespiratory fitness were not significantly different between groups at 24 or 36 months (both p > 0.1).InterpretationThe SCA did not prevent weight gain compared with monitoring alone at 2 or 3 years in adults with overweight or obesity. On average, we observed prevention of weight gain in both arms of the trial.Trial RegistrationClinicalTrials.gov, no. NCT02027077.© 2022 CMA Impact Inc. or its licensors.

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