Objectives: The objectives of the study are to characterize the frequency and size of small weight gains during behavioural weight loss treatment and to evaluate the relationship between small weight gains and weight loss outcomes.
Methods: Participants (n = 281) in a year-long behavioural weight loss programme were weighed at treatment sessions, and between-session weight gains were classified into several categories based on size. The occurrence of different gain magnitudes and their relation to weight loss were examined during both the active weight loss (months 1-6) and weight loss maintenance (months 7-12) phases of treatment.
Results: Weight gains were common during both phases of treatment, with smaller gains occurring more frequently than larger gains. Greater frequency of all gain magnitudes was associated with lesser weight loss during both phases. Additionally, participants who had just one or two weight gains of the smallest size examined (1.0-1.9 lb) lost less weight than those who had no gains.
Conclusions: Small gains appear to reflect true weight gain due to poor adherence to behavioural recommendations and are associated with worse weight loss outcomes, even when limited in number. Future research should examine how best to prevent small weight gains from occurring and how clinicians and participants should respond when a weight gain does occur to promote weight control success.
Keywords: Behaviour therapy; clinical practice; weight change; weight gain.