The Keto diet is a high fat and low-carb diet. In a keto diet, you deprive yourself of carbohydrates. Hence, your body starts to run on glycogen stores within your muscles and liver for fuel.
It usually takes four to five days to burn through all those carbs and ultimately start shifting into the state of ketosis. Now when you deprive yourself of all those carbs, your liver starts converting fat into ketone bodies for survival.
Suppose you are a high-intensity athlete or perform a heavy physical workout; in that case, the keto diet may not be the best diet for you. You will find yourself weaker because those activities involving high-intensity physical activities require energy produced from ATP production. This ATP production is predominantly run on glucose.
However, if you are not very physically active, then a low-carb ketogenic diet can work very well for you.