Recommendations for prevention of weight gain and use of behavioural and pharmacologic interventions to manage overweight and obesity in adults in primary care

The review identified evidence from 19 RCTs that focused on preventing weight gain in mixedweight populations (i.e., populations with normal- weight, overweight and obese adults) through lifestyle, diet and/or exercise, as compared with no intervention.16 Trials that enrolled only people with conditions predisposed to weight gain and associated adverse health effects (e.g., polycystic ovary or metabolic syndrome) or eating disorders were excluded from the systematic review. Trials of pharmacologic and surgical interventions were also excluded because these interventions were not considered relevant for prevention of weight gain among normal-weight individuals. To ensure the trials included some adults of normal weight, the number or percentage of nonnal-weight participants needed to be specified, or at least one study ann needed a baseline mean BMI or a baseline mean BMI minus one standard deviation that fell within the normal range (18.5-24.9). Power was likely sufficient in meta-analysis for assessment of the weight-change outcome (n = 48 460 for all studies). Behavioural interventions (which generally included diet, exercise or other lifestyle components) lasted between 3 and 12 months to up to 12 years.16 Few studies exist that are designed to help patients of normal weight with or without specific health risks to maintain their weight. Such studies in both solo-practitioner and team-based care delivery models are needed. As such, this guideline was limited in its ability to comment on prevention of weight gain in normal-weight populations, because the data are largely based on trials from mixed-weight populations. As overweight and obesity rates continue to rise in Canada, it becomes increasingly important for practitioners to understand how adults of normal weight can best maintain their health over time, and whether structured interventions beyond standard advice for healthy living should be implemented with normal-weight populations. It is also important to better understand additional benefits in improved functioning and quality of life that could result from interventions. Research is needed on predictors of future health risk associated with weight gain. More research is also needed on patients' experiences with preventive interventions and their preferences about receiving these interventions, in order to prevent weight gain and the associated health risks. The average weight and BMI of Canadian adults have increased over the last 40 years, wit