If-then plans are concrete action plans that specify, in an if-then format, where, when, and how one will act in order to achieve a specific goal-directed behaviour (Gollwitzer, 1993). This study examined whether making if-then plans to engage in daily life physical activities (DLPA) results in greater weight loss compared to gym-related physical activities (GRPA). We hypothesized that DLPA will result in greater weight loss than GRPA because DLPA are more feasible and achievable than GRPA. DLPA should thus be more likely to be carried out and contribute to weight loss. ata from a sample of overweight/obese participants (BMI range of 28 to 45 kg/m2) who partook in the 12-month McGill CHIP Healthy Weight Program were collected. The program was designed to teach participants to change various habits through lifestyle changes (e.g., taking the stairs, cycling to work, taking fitness classes). The number and specificity of DLPA and GRPA if-then plans, as well as participants' weight were assessed at every session, for a total of 22 sessions. Multi-level analyses examined the effect of the number and specificity of DLPA plans relative to those of GRPA plans in predicting changes in weight during the program.