Two 3-month longitudinal studies examined weight loss following a 1-month behavioral intervention (FIT-DSD) focusing on increasing participants’ behavioral flexibility and breaking daily habits. The goal was to break the distal habits hypothesized as playing a role in unhealthy dietary and activity behaviors. The FIT-DSD intervention required participants to do something different each day and to engage in novel weekly activities to expand their behavioral repertoire. These activities were not food- or exercise-related. In Study 1, the FIT-DSD program was compared with a control condition where participants engaged in daily tasks not expected to influence behavioral flexibility. Study 2 used an active or quasicontrol group in which half the participants were also on food diets. Measures in both studies were taken pre-, post-, and post-postintervention. In Study 1, FIT-DSD participants showed greater weight loss that continued post-postintervention. In Study 2, all participants on the FIT-DSD program lost weight, weight loss continued post-postintervention, and participants who were also dieting lost no additional weight. A dose relationship was observed between increases in behavioral flexibility scores and weight loss, and this relationship was mediated by calorie intake. Corresponding reductions in BMI were also present. Increasing behavioral flexibility may be an effective approach for tackling obesity and also provides affective and potential life-skill benefits.