It is normal to lose 1 pound in 1 day, which may be a loss of water and intestinal contents; but it is not normal if it is a loss of protein, fat, etc. The weight of the human body can vary by 3-5 pounds at different times and states. If the morning fasting is lighter than before going to bed the night before, because the body’s water after a night through breathing, urine loss, not timely replenishment, so it is easy to have a weight change. Lighter before meals than after meals, and lighter after exercise than before exercise, is the loss of water and intestinal contents resulting in weight difference, is generally normal. But if a day of protein and fat and other nutrients lost 1 pound is not normal. Generally speaking, weight loss a day to reduce about 100g of fat has been a very ideal level, the human body only in the metabolic rate of a serious malfunction, such as hyperthyroidism, severe diabetes, malignant fluid, may be a day to lose 1 pound of protein and fat and other nutrients.