Oct 6, 2013 Start by determining your maintenance Kcals. I.e. How much food does it take to maintain your current weight? How many Kcals does that add up to? That is your maintenance Kcals. Then, calculate your % lean body mass. If you are at 20% bf and weigh 250 lbs you have 50lbs of fat and 200lbs of lean body mass (LBM). Maintenance Kcals should be around 3,800Kcals per day for a moderately active person at this weight and LBM. For your diet you should start out 250 to 500Kcals below maintenance each day. In this example you will eat around 3,300Kcals per day if you are in a 500Kcal defecit. For a ketogenic diet you will eat mostly protein, and quite a bit of fat, with trace carbs. You should eat 1.5 to 2 g protein per lb lean bodymass. So to start, try eating 2g per lb LBM which equals 400g protein. At 4Kcals per g, this is 1,600kcals. The remaining 1,700Kcals should be made up from fat. at 9Kcals per g that equals 189g fat per day. The carbs should be trace, so only 1/4 cup of fibrous veggies per meal a few times per day. Voila, there is your ketogenic diet. Next comes the fun part: the menu!