Submitted to: Physiology and Behavior
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/24/2011
Publication Date: 4/30/2011
Citation: Witbracht, M.G., Laugero, K.D., Van Loan, M.D., Adams, S.H., Keim, N.L. 2011. Performance on the Iowa gambling task is related to magnitude of weight loss and salivary cortisol in a diet-induced weight loss intervention in overweight women. Physiology and Behavior. 106(2):291-297. https://doi.org/10.1016/j.physbeh.2011.04.035.
Interpretive Summary: Even when dieters adhere to a well-controlled weight loss diet, the amount of weight lost varies widely among individual dieters. In this study we tested if decision-making ability was related to the amount of weight lost when women remained on a calorie-reduced, weight loss diet for 12 weeks. We found that the amount of weight lost was associated with performance on a computer-based card game that measures thoughtful decision making; those that lost more weight performed better. We also observed that when the dieters were allowed to choose foods from a self-service buffet offered in a laboratory setting at the end of the study, those women who ate more calories on this occasion lost less weight over the 12 week study. These results suggest that the ability to lose weight may be linked to decision-making about events or behavior with emotional or social importance, such as a person’s ability to ignore immediate reward (overeating palatable food) when long-term consequences are beneficial (weight loss). Our study was not designed to demonstrate cause and effect; additional studies of this phenomenon are needed.
Technical Abstract: The overall objective of this study was to examine the relationship between executive function, specifically decision making, and weight loss. We used the Iowa Gambling Task (IGT) to characterize decision making and compared performance on this task to weight loss in obese women (n=29) participating in a 12-week controlled, calorie-reduced intervention. We hypothesized that a greater amount of weight loss over the course of the intervention would be associated with better performance on the IGT, assessed at the end of the intervention. The intervention led to significant weight loss of 5.8 ' 3.1 kg (p<0.05) and fat loss of 5.1 ' 3.0 kg (p<0.05). Body weight and fat mass losses over the 12-week intervention varied widely, ranging from -12.5 kg to 0.0 kg for body weight and -10.4 kg to +0.8 kg for fat mass. A greater amount of body weight loss was correlated (r = 0.425; p<0.01) with a higher total score on the IGT. Similarly, the reduction in body fat mass was also correlated with the IGT score (r=0.408; p<0.05). We examined other physiological (salivary cortisol), metabolic (resting metabolic rate), and behavioral (food intake; dietary restraint) factors that might be related to differences in the magnitude of weight loss. Of these variables, ad libitum consumption of energy and fat during a buffet meal were inversely related to weight loss (r = -0.428; p<0.05 and r = -0.375; p<0.05, respectively). The present study is the first to report an association between diet-induced weight loss and performance on the IGT, and this association was specific to the loss of body fat. Our results suggest that differences in weight loss may be linked to executive function that involves decision making about events that have emotionally or socially salient ramifications. These findings underscore the need to further investigate higher cognitive and neuroendocrine pathways that may influence or be altered by the process of dieting and weight loss.