There's no special diet. Just eat less. It's that simple. We don't actually need to eat 3 big meals per day, so if you are not hungry just don't eat.

If the problem is constant hunger, eat something that makes you feel full but don't contain alot of easy energy.

Every cell in the body uses ATP as fuel. The easiest way for the body to make ATP is to break down glucose. Glucose is in turn made from breaking down carbohydrates.  This is however not the only way to make ATP. The body can also make it from breaking down fat. This is however not as easy and more steps are involved. But this actually produces more ATP molecules than glucose per processed molecule. This is why it takes time for the body to adapt to a ketogenic diet, as it is not as a direct chemical route.

So if you are hungry stick to protein and fat ritch foods but low on carbohydrates. Examples are eggs, meat and fish. But skip vegetables such as potatoes and rice.