Dr. Stephen Phinney, who coined the phrase “nutritional ketosis,” stresses the importance of keeping protein moderate, carbs low, and eating fat to satiety. Too much protein will result in the excess getting converted to glucose, thus stimulating insulin production. Carbohydrate above a certain amount also stimulates insulin production. The exact amount varies from person to person. Dr. Phinney calls anything below 100 to 125 grams a day low-carb, but a lot of people are so insulin-resistant that these forums recommend an upper limit of 20 grams to ensure that you get into ketosis. But the key is not to restrict calories, because the body reacts to calorie restriction by slowing down your metabolism instead of burning fat. So all those carbs you’re not eating? Replace them with fat!
If you do that, your body will tell you when you’ve had enough at each meal, and it will then start burning both the fat you’re eating and your body fat. One study even had a participant who still lost body fat even while eating as much as 3,000 calories a day, almost all of it fat. So contrary to the received wisdom and government guidelines, fat is your friend, not your enemy.