Reinforcing Relative Value (RRV) of food and impulsivity are associated with energy intake and obesity. This study investigated the degree to which changes in RRV and impulsivity independently or interactively predict changes in body weight and composition in women with overweight or obesity engaged in either fast or slow weight loss programs. Body weight, body composition, impulsivity (Barratt Impulsiveness Scale), and RRV snack (computerized Behavioural Choice Task) were measured at baseline and post-intervention in 30 women with obesity undergoing either slow (n = 14, -500 kcal/day, 20 weeks) or fast (n = 16, -1000 kcal/day, 10 weeks) weight reduction. No group × time effects were noted on body composition, impulsivity, or RRV, so participants from both groups were pooled for analysis. Multiple regression analyses indicated that none of the impulsivity variables predicted weight or fat mass (FM) loss. However, ΔRRV snack predicted ΔFM (r = 0.40, p = 0.046), whereby greater increases in RRV snack were associated with less FM loss. The results indicate that different rates of weight loss do not differentially affect RRV snack or impulsivity traits. However, changes in RRV snack predicted FM loss, suggesting that dietary interventions that either mitigate increases or foster reductions in the RRV snack may yield greater reductions in adiposity. Trial Registration clinicaltrials.gov identifier: NCT04866875. Novelty: No differences in RRV of food were noted between fast and slow weight loss. Weight loss from combined fast and slow groups led to a moderate-sized reduction in total impulsivity. Greater diet-induced increases in RRV snacks were associated with less body fat loss.
Keywords: delay discounting; impulsivity; impulsivité; mépris des gains différés; perte de poids; reinforcement; renforcement; weight loss.