Yeah, it does sound weird, doesn’t it? Dr. Jason Fung explains it this way: “We burn what we eat. When we eat sugar (carbohydrate), we burn sugar. So if we want to burn fat, we need to eat fat.”
That’s a cute way to put it, but the real issue is the limiting of carbohydrate. Carbohydrate stimulates insulin production, and insulin is the hormone that tells the body to store fat, so if we want to let the fat out of our fat tissue, we need to lower insulin. We lower insulin by eating less carbohydrate. Your actual carbohydrate limit may be higher than 20 g/day, but start eating no more than that much carbohydrate each day, and you are practically guaranteed to get into ketosis and start burning fat.
So if you are not going to eat carbohydrate, what should you eat? Well, just continue eating the same amount of protein, for now, and replace all those missing calories from carbohydrate with calories from fat. Fat has almost no effect on our insulin level, which makes it a safe source of energy. Fat also has more than twice the number of calories per gram as carbohydrate does, so it takes a lot less to satisfy us. Eat enough protein and fat at each meal so that you are not hungry again for quite some time. Don’t eat again until you are hungry again. As you learn to listen to your body, your body will start telling you how much to eat.