Fasting is a practice that dates back centuries and plays a central role in many cultures and religions. Fasting is not eating all or some foods or drinks for a set period of time, there are many different ways of fasting. In general, most types of fasts are performed over 24–72 hours. Intermittent fasting, on the other hand, involves cycling between periods of eating and fasting, ranging from a few hours to a few days at a time. Fasting has been shown to have many health benefits, from increased weight loss to better brain function. 'Alternate day fasting (ADF) improved markers of general health in healthy, middle-aged humans while causing a 37% calorie reduction on average. No adverse effects occurred even after >6 months. ADF improved cardiovascular markers, reduced fat mass (particularly the trunk fat), improving the fat-to-lean ratio, and increased β-hydroxybutyrate, even on non-fasting days.' (6)