Every human body has a biological rhythm that can adapt to the environment through light exposure, food intake and exercise. When our biological rhythm is disrupted regularly, for example due to night shifts, this can lead to the development of type 2 diabetes. This thesis investigated the metabolic health effects of adjusting the timing of exercise and food intake to the biological rhythm. The thesis showed that advancing the evening meal and thereby extending the fasting period can increase night time fat oxidation in both healthy people and people at risk for type 2 diabetes. In people with type 2 diabetes, the 24-hour glucose levels and fasting glucose levels of participants with type 2 diabetes improved after they restricted their food intake to a period of 10 hours per day for 3 weeks. SGLT-2 inhibitors (a type of medication) can also cause the body to fast more, as it leads to extra urinary glucose loss. Treatment with this medication increased fat oxidation and lowered 24-hour glucose levels in participants at risk for type 2 diabetes. Furthermore, it turned out that the 24-hour rhythm in fat and glucose oxidation, but not in energy expenditure, depended on food intake. So for our metabolism it matters at what time of day we eat and especially how long we fast.