Objective The objective of this study was to examine how sensitivity to short-term reward and longterm goal perseverance are related to body mass index (BMI; kgm²) in a large sample of men and women with and without obesity. Methods A total of 450 participants (56.2% male; 73.1% non-Hispanic White) with mean ± standard deviation age of 30.7 ± 10.4 years and BMI of 29.3 ± 8.2 completed online versions of the Delayed Reward Discounting task to measure sensitivity to short-term reward and the Grit Scale to measure long-term goal perseverance. Results In regression analysis, higher sensitivity to short-term reward (i.e. a preference for receiving smaller rewards after a shorter delay; b = 0.49, p = 0.016) and lower long-term goal perseverance (b = 1.26, p = 0.042) were independently associated with higher BMIs. Individuals with a favourable score on one measure were not ‘protected’ from the risk associated with an unfavourable score on the other measure. Conclusions An overvaluation of short-term reward (e.g. the taste of palatable food and the comfort of engaging in sedentary activities) and undervaluation of long-term health goals (e.g. achieving a healthy weight and avoiding obesity-related comorbidities) may contribute to excess weight. Additional research incorporating prospective experimental designs is needed to determine whether decision-making strategies can be targeted to improve weight management.