I would like to know how and the what nots and the possible disadvantages or health risks
Intermittent fasting is a pattern of eating that focuses on limiting the amount of time you eat each day. For example, you could set aside time to eat for 6 hours (eating window) and not eat for 18 hours (fasting window). We shorthand that as 18:6. The amount of fasting time is up to you, but commonly between 16 and 24 hours fasting is considered Intermittent Fasting.
Autophagy is a benefit of Intermittent Fasting. It is a process where the body recycles and cleanses itself on the biochemical level. It is prominent at 18 hours or more of fasting.
Increased insulin sensitivity is another benefit. That means your insulin is more efficient. A cause of type 2 diabetes and cardiovascular diseases is insulin resistance, where the body produces too much inefficient insulin. Fasting ensures that insulin is spiked less often in the blood. For best results, I combine intermittent fasting with a low carb, moderate protein, high fat, and high vegetable diet commonly known as healthy ketosis.
As far as disadvantages go, in my experience there are none.