Water fasting isn't new. People have been practicing it for decades due to different reasons - religious/spiritual fasting being one of the oldest. You might also need to fast before a medical procedure. Regardless of the reason, starving your body for a certain amount of time has certain proven benefits, such as promoting autophagy. 
Water fast usually lasts between 1 and 3 days. If you've never stood for such a long period without eating, you should get your body accustomed to it by slowly decreasing your eating window. Intermittent fasting is a healthy way to start.
For people who fast for long periods of time, the post-fast stage is vital. You should return to light or small meals. If you eat too much at once, you will experience disturbing symptoms. The post-fast stage, after a very long water fast, predisposes your body to refeeding syndrome, therefore you cannot negligently break the fast.
Nowadays, most people include water fasting in their diets; they either want to speed up the weight loss process, detox, or both. Others choose it due to its health benefits. However, water fasting also has its cons. The following slides will help you decide whether or not to embark your body on a journey during the upcoming year.
You could survive on water and nothing else for a maximum period of 72 h without medical supervision. Water fasting may prevent cancer. Autophagy cleans your body from damaged cells and eliminates intracellular pathogens. The process helps your body get rid of unwanted components, and it is crucial in preventing all kinds of diseases. 
Water fasting may be capable of improving your body's sensitivity to leptin and insulin. The first hormone helps your body feel full. If you have leptin sensitivity, your body will be able to catch those hunger signals faster, which results in lower obesity risk. The second hormone deals with the metabolism of nutrients, mainly carbohydrates. Insulin sensitivity means better blood sugar levels.  
Overall, water fasting might play a key role in your health management.
Obese people benefit from water fasting more than lean people do. The reason is that it can make you lose the wrong kind of weight. You can shed pounds fast, but also muscle mass. It's not suitable for an athlete. Because muscles need nutrients to recover, you might want to consider this aspect before water fasting.
Postural hypotension is another disadvantage of water fasting. You experience low blood pressure when you get up rapidly. The medical condition can cause more symptoms such as dizziness, vertigo, faintness, and the feeling of being close to losing your conscience. Feelings of lightheadedness interfere with your daily life, and risking having an accident because of willingly starving is not desirable.
Water fasting can also worsen chronic diseases. People who have gout, diabetes, heart issues, eating disorders, or other conditions cannot water fast without the physician's consent. Depriving your body of essential nutrients, while in a sensitive state, might have unpleasant consequences. 
on January 9, 2020