The key to a well-formulated ketogenic diet is to keep your carbohydrate intake at a level that will lower your insulin level. The rest is simply keeping protein at a good level and filling in the remainder of calories by replacing carbohydrate with fat. We say “eat fat to satiety,” which means to eat when you’re hungry, to stop eating when you stop being hungry, and not to eat again until you’re hungry again—ignore the clock, in other words.
In the first two or three weeks, you may seem to be eating a lot of food. Don’t worry about it. At some point, the lowered insulin will allow the peptide YY from your stomach and the leptin from your fat tissue to start registering again in your brain, and your appetite will become an accurate guide to however many calories your body needs on any given day. If you have a lot of excess fat to lose, you may notice a surprising moment when all of a sudden you really stop being hungry. (For me, it happened in the middle of a meal, and it was a stunning surprise.)
You may or may not lose weight on a ketogenic diet, but you probably can expect some body recomposition. Giving your body enough energy by eating to satiety lets your body set your appetitie to a level at which it can burn off excess fat, while making use of all the calories you eat to heal your metabolism, reverse your insulin resistance, clear up your visceral fat, get your mitochondria going again and get them burning fat instead of glucose, and so forth. You may well put on muscle and increase your bone density, even while losing excess fat.