There's a lot of quibble about what keto consists of, and it's because everyone's body reacts a bit differently. Keto cuts out all sugars, all grains and beans. It's a low carb (@ 20 carbs/day), high fat and moderate protein diet. It encourages butter, bacon, salads, some veggies, and unprocessed foods. It's effective, but it is hard to sustain for some people. It's often used as a sort of gateway to Paleo.