Fasting Is Essential to Staying Healthy: Diet, Fasting, and Your Circadian Clock:

Diet, Fasting, and Your Circadian Clock:

Having periods of fasting in your day are very important to maintain a robust circadian rhythm. This in turn provides health benefits. Fasting not only affect the ability of the brain to regulate your Circadian Clock but also other organs, such as your liver and possibly kidney. 

There was a study where mice were given a high-fat diet only during normal waking hours. They restricted the time the mice were allowed to feed. These mice compared to control (non-restricted---able to eat at all times as desired) had a larger amplitude of expression of circadian clock genes and these mice were less likely to become obesity, have metabolic dysfunction, and liver damage. (Ref 1, 2).

Human studies have yet to be done and it will take years to do a good human study, but it makes sense that "When" you eat matters just as much as "What" you eat. 

Many religions have practiced fasting for years. They have it right: fasting from meat often is a very good idea. Fasting from sundown to sun up is a good idea. Fasting all together is also likely a good idea for certain patients who are healthy enough to do this (always check with your MD if you have any health issues). 
We now have science to back up the health benefits that fasting can give.  

1. Hatori M, et al. Time-restricted feeding without reducing caloric intake prevents metabolic diseases in mice fed a high-fat diet. Cell. Metab. 2012;15:848–860. doi: 10.1016/j.cmet.2012.04.019.

2. Chaix A, Zarrinpar A, Miu P, Panda S. Time-restricted feeding is a preventative and therapeutic intervention against diverse nutritional challenges. Cell. Metab. 2014;20:991–1005. doi: 10.1016/j.cmet.2014.11.001