The human body is the equivalent of a machine or a car whose engine can never be stopped. The heart will beat , the lungs will contract and expand continuously , the blood will flow continuously , the intestines will digest food and the kidneys will continue to purify. If you want to move your arms and legs, your muscles will start to move along with the cells of other muscles. All of this requires energy , just as petrol is needed to drive a car. This energy we get from food. The unit of energy is calories. If we do not move our body muscles then our body needs 1000-1200 calories in 24 hours. If the way of life is comfortable then 1600 calories are required. A worker needs 3,000 calories and an Eskimo living in Greenland needs 5,000-6,000 calories. We digest all these foods in our stomach i.e. Tantra. The juice that is secreted from the digested food is absorbed into the blood. Every cell in the body receives it from the blood and produces energy in the mitochondria. Eating 1800 calories a day fills the stomachs of countless cells in our body. If we consume extra calories, it becomes fat. If we do not eat anything throughout the day, then these stored fats provide energy to the body. Just as we use gasoline to drive a car , it is also a matter of increasing or decreasing our body weight. If a car holds 10 liters of petrol , we will pour 10 liters of petrol in it. But if we pour 15 liters of oil into the tank, the oil will overflow because the amount of oil will be more than the size of the tank. This also applies to our body. If our body needs 1600 calories per day and if we eat that much then our body weight will remain the same. But if we consume 2000 calories per day , the extra calories will be converted into fat which will increase the obesity of our body and if it continues then the accumulated excess fat will cause obesity.