It is common to lose a lot of weight in the first two weeks after starting the ketogenic diet – about 4-10 lbs or 2-5 kg on average. A large part of this initial weight loss is water that was previously bound in the carbohydrate (glycogen) stores of your body. After the first two weeks, the average weight loss is about 1-2 lbs or 0.5-1kg per week. How fast you burn fat on keto also depends on other factors, such as whether you practice intermittent fasting or exercise.