The stomach is a muscular sac that is important for absorbing food and preparing food for further digestion.
Calorie is a unit of measurement and is defined as the amount of energy that is required to raise the temperature of 1 kg of water by 1 degree C. Calorie is often associated with food and is a simple way to describe the amount of energy a person's body receives from eating and drinking. Once calorie is also equivalent to 4.184 joules, which is a common unit of energy. The nutritional information on food packages is generally mentioned in kcal. Technically 1 kcal is equal to 1000 calories; however, kcal is referred to as calories in general practice. Different foods have different amount of calories. This occurs due to the difference in composition of different foods. The per gram value of calories in carbohydrates, fats and proteins varies. Carbohydrates contain 4 calories in a gram, fats have 9 calories in a gram and proteins have 4 calories in a gram.