Validation of the Food Purchase Task (FPT) in a clinical sample of smokers with overweight and obesity.

Obesity is a major health problem associated with disease burden and mortality. In this context, analyzing food as a powerful reinforcer from a behavioral economics framework could be relevant for the treatment and prevention of obesity. The purposes of this study were to validate a food purchase task (FPT) in a clinical sample of Spanish smokers with overweight and obesity and to assess the internal structure of the FPT. We also analyzed the clinical utility of single-item breakpoint (i.e., commodity price that suppresses demand). A total of 120 smokers [% females: 54.2; M = 52.54; SD = 10.34] with overweight and obesity completed the FPT and weight/eating-related variables. Principal component analysis was used to examine the FPT structure, and a set of correlations were used to examine the relationship between the FPT, eating and weight-related variables. The FPT demonstrated robust convergent validity with other measures of eating. Higher food demand was related to higher food craving (r = .33), more binge eating problems (r = .39), more weight gain concerns (r = .35), higher frequency of both controlled (r = .37) and uncontrolled (r = .30) grazing, as well as to an eating style in response to emotions (r = .34) and external eating (r = .34). Of the demand indices, Intensity and O showed the highest magnitudes of effects. The FPT factors, persistence and amplitude, do not improve individual FPT indices; and the single-item breakpoint was not related to any eating or weight variable. The FPT is a valid measure of food reinforcement with potential clinical utility in smokers with obesity/overweight.