Food and water are essential to survival, but there are times when fasting is necessary to facilitate optimum physical health. One health care practitioner observes that ‘fasting is simply a process of deep physiological rest. This rest period helps you rebuild functioning power and recover from the energy dissipation caused by hectic daily schedules and abusive living habits (Frank Sabatino, D.C., Ph.D.).’ Another notes that ‘regulatory and reparative processes of the body are given unimpeded encouragement by the temporary omission of food (William Esser, N.D., D.C.).’ When the gastrointestinal system is resting from digesting and absorbing food, then all other systems benefit. There are different types of fasting. In normal circumstances, it may be imposed or an act of choice. Your family physician requests it before an annual physical examination and before some surgical and diagnostic procedures. Many faith groups practise fasting as a spiritual exercise for a variety of reasons. It can vary from skipping a meal to a liquid 24-hour (or longer) fast to a complete/dry fast for one or more days. Whatever your reason for fasting and whatever type of fast you choose, there are physical and spiritual benefits of this practice. This article addresses some of the physical benefits. Of course, this is not in any way exhaustive and does not mean to replace recommendations from your health care professional. During a fast, the energy needed for regular digestion is re-routed to other systems to boost their performance. One of these is the cardiovascular system, according to Dr. Donald Hensrud (Mayo Clinic). He reports that while researchers are still unsure why, regular fasting can potentially improve heart health. He observes that while more studies are needed, current research indicates that ‘periodic fasting and better heart health may be linked to the way your body metabolizes cholesterol and sugar. Furthermore, he adds that regular fasting can decrease low-density lipoprotein (“bad” cholesterol) and may improve the way the body metabolizes sugar, thus reducing the risk of weight gain and diabetes – both of which are implicated in heart disease. The brain also benefits from fasting. Peer-reviewed scientific research on the benefits of fasting on the mind/brain is limited, but anecdotal evidence is abundant. Those who fast weekly or monthly report that they feel lighter and more energetic, can think more clearly, and enjoy a healthier spiritual experience. They also report experiencing greater self-discipline to approach work or other assignments and personal projects with a level of vigour that accompanies or follows a fast. Perhaps that’s why Moses, Ezra, Elijah, Esther, Daniel, Jesus, and Paul (to name a few) fasted before, during and after significant events, especially when significant decisions that required clear thinking and focus were pending. Some research is indicating that intermittent fasting, in particular, maximizes brain function. This type of fast ‘includes everything from periodic multiday fasts to skipping a meal or two on certain days of the week, (and) may also lower the risks of degenerative brain diseases in later life (David Stipp, Scientific American, 2013).’ With all these benefits and more, you may want to consider incorporating a regular fast as part of a balanced, healthy practice unless you are dealing with specific medical conditions. Unless it is medically supervised for a particular diagnostic, medical or surgical procedure, fasting may not be for you. If you (a) are pregnant, (b) are taking medication for a short-term or chronic medical condition, (c) are diagnosed with a wasting disease or malnutrition, (d) have a history of cardiac arrhythmias, hepatic or renal insufficiency or a compromised immune system, then you should discuss this with your primary health care practitioner (Fuhrman). Fasting is also not recommended as a means of losing weight partly because fasting slows the body’s metabolic rate, so your diet from before the fast is even more fattening after you fast (Fuhrman )’. Weight loss is inevitable with drastically reduced caloric intake. Much of the initial weight loss is water. During fasting, the body assumes a conservation mode and burns calories more slowly (Kathleen M. Zelman, MPH, RD, LD). Dramatic reduction in calorie intake means that you will lose weight - primarily fluid. ‘Once you resume eating, much of the weight returns because when the metabolism slows, there is a greater chance of gaining weight and ‘the weight that is regained is likely to be all fat--lost muscle has to be added back at the gym ( Zelman).’ This article would not be complete without presenting the possible side effects of fasting – particularly if repeated and/or long-term. These include dizziness, headaches, low blood sugar, muscle aches, weakness, fatigue, anemia (in long fasts), a weakened immune system, liver and kidney problems, irregular heartbeat, vitamin and mineral deficiencies, muscle breakdown, diarrhea, an increased risk of fluid imbalance and dehydration (Zelman). If you plan to fast for an extended period, you must consult your health care practitioner to ensure that it is safe and effective.