RecruitingBehavioural interventionThe Metabolic Effects of Intermittent FastingCaloric restriction has beneficial metabolic effects in humans including weight loss and improvement in blood pressure and lipid levels. Intermittent fasting has emerged as a popular alternative to caloric restriction as it does not require daily adherence to a dietary protocol, but whether the benefits of fasting protocols are dependent on weight loss is not known. In this study, the investigators will explore the metabolic effects of fasting and evaluate whether these effects, including negative effects on bone metabolism, are independent of weight loss.