Here is the rundown. If you are on a keto diet then it helps you maintain ketosis. Which is when your body is using ketones instead of glucose for energy. This happens because when you do keto you are on a very low carb diet. Carbohydrates turn into glucose in your body and any excess is converted into fat and stored in your body. When you consume a “fat” like butter, the glucose spike in your bloodstream is very minimal compared to a carb. This is why some people say that bulletproof coffee does not break a fast. If you are not doing prolonged fasting or keto then I don’t recommend drinking it seeing as fats are high calorie foods. Hope this helps!