That's because keto isn't really a weight loss diet. It can be, but it was designed to reduce seizures in people with epilepsy. It's a healthy diet with the side effect of reducing weight if calories are reduced. It is popular as a way to lose weight because the fats keep you satiated for hours, reducing hunger and the feeling of needing to eat. Also, the reduction of carbs reduces the blood sugar spike and the subsequent sugar crash later that makes you feel hungry.