Secondary objectives/hypotheses: The effects of MPH on all components of energy expenditure will be investigated. Based on the investigators' pilot data, it is predicted that from Baseline to 60 days, MPH will increase total energy expenditure (TEE) when compared with placebo, mostly through greater resting energy expenditure (REE) and thermic effects of food (TEF). It is hypothesized that after the 60-day intervention the MPH group will experience a significantly attenuated reduction in REE compared to placebo. We predict that the MPH group will lose body weight at 2 months, whereas, it is predicted that there will be no change in body weight for the placebo. The investigators will also explore the effects of MPH on macronutrient preference and consumption, and on the rewarding value of energy dense snack foods. Based on previous findings, the investigators predict that MPH will reduce consumption of energy dense, high fat/sugar foods but have little effect on consumption of foods low in calories, fats or sugars. In addition, it is predicted that the reduction in intake of energy dense, high fat/sugar foods will be mediated by reductions in the rewarding value of food and impulsivity as measured by well validated computerized simulations. Also explored will be the effects of MPH on olfaction and it is predicted that compared to placebo, individuals taking MPH will have reduced smell function. It is also predicted the MPH group will show reduced appetite sensations, reduced rewarding value of food, reduced impulsivity for snack food, and reduced palatability ratings of food compared to placebo at 2 months.