Financial incentives have been used successfully to promote health behaviors, however they may be counterproductive if they "crowd out" pre-existing intrinsic motivation and lead to a decrease in performance once incentives are removed to a level lower than they had never been introduced. We provide new evidence that incentives do not crowd out intrinsic motivation in the case of weight loss. We measure motivation via a survey administered before and after the introduction of financial incentives in two weight loss field experiments and find no evidence that intrinsic motivation fell among participants receiving incentives compared to control participants who do not receive incentives.