Abstract
Obesity is associated with poorer executive functioning and reward sensitivity. Yet, we know very little about whether weight loss through diet and/or increased exercise engagement improves cognitive function. This study evaluated whether weight loss following a dietary and exercise intervention was associated with improved cognitive performance. We enrolled 125 middle-aged adults with overweight and obesity (98 female) into a 12-month behavioral weight loss intervention. Participants were assigned to one of three groups: energy-restricted diet alone, an energy-restricted diet plus 150 min of moderate intensity exercise per week or an energy restricted diet plus 250 min of exercise per week. All participants completed tests measuring executive functioning and/or reward sensitivity, including the Iowa Gambling Task (IGT). Following the intervention, weight significantly decreased in all groups. A MANCOVA controlling for age, sex and race revealed a significant multivariate effect of group on cognitive changes. Post-hoc ANCOVAs revealed a Group × Time interaction only on IGT reward sensitivity, such that the high exercise group improved their performance relative to the other two intervention groups. Post-hoc ANCOVAs also revealed a main effect of Time, independent of intervention group, on IGT net payoff score. Changes in weight were not associated with other changes in cognitive performance. Engaging in a high amount of exercise improved reward sensitivity above and beyond weight loss alone. This suggests that there is additional benefit to adding exercise into behavioral weight loss regimens on executive functioning, even without additional benefit to weight loss.
Highlights
More than one third of the U.S population meets criteria for obesity (i.e., a body mass index (BMI) ≥ 30.0 kilograms/meter2) and approximately 68% of adults in the U.S are consideredNutrients 2020, 12, 2988; doi:10.3390/nu12102988 www.mdpi.com/journal/nutrientsNutrients 2020, 12, 2988 overweight (BMI ≥ 25.0 kg/m2 ) [1]
This study examined the effects of a behavioral weight loss intervention consisting of an energy restricted diet and exercise on cognitive performance in 125 sedentary adults with overweight and obesity
The intervention was effective at reducing weight across all participants, in contrast to our hypotheses, there was no moderation by intervention group despite prior evidence and weight loss guidelines indicating a dose-response of exercise [36]
Summary
More than one third of the U.S population meets criteria for obesity (i.e., a body mass index (BMI) ≥ 30.0 kilograms/meter (kg/m2 )) and approximately 68% of adults in the U.S are considered. In the context of executive functions (e.g., inhibitory control, set-shifting, working memory, decision-making), higher BMI is associated with poorer task performance regardless of whether the individual meets criteria for obesity [7] This suggests that even small to modest amounts of extra weight could negatively impact executive processes critical to regulating health behaviors, including diet and exercise, which may exacerbate the vicious cycle of weight gain and, in turn, limit weight loss or weight loss maintenance. We evaluated whether exercise, in combination with an energy-restricted diet, could improve cognitive functioning beyond weight loss through diet alone (i.e., a dose-response effect of exercise) To accomplish these aims, we measured cognitive function in adults with overweight or obesity using a battery of reward and executive functioning tasks both before and immediately after 12 months of a behavioral weight loss intervention involving: (1) diet modification only, (2) diet plus 150 min per week of exercise, or (3) diet plus 250 min per week of exercise. We predicted a dose-response effect of exercise, such that intervention effects on cognitive functioning would be greatest in the group receiving the most exercise, followed by the moderate exercise group, and that the smallest effects would be observed in the diet-only group
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