Food energy is energy that animals (including humans) derive from their food, through the process of cellular respiration, the process of joining oxygen with the molecules of food (aerobic respiration) or of reorganizing the atoms within the molecules for anaerobic respiration.
Humans and other animals need a minimum intake of food energy to sustain their metabolism and drive their muscles. Foods are composed chiefly of carbohydrates, fats, proteins, water, vitamins, and minerals. Carbohydrates, fats, proteins, and water represent virtually all the weight of food, with vitamins and minerals making up only a small percentage of the weight. Some diet components that provide little or no food energy, such as water, minerals, vitamins, cholesterol, and fibre, may still be necessary to health and survival for other reasons. Water, minerals, vitamins, and cholesterol are not broken down (they are used by the body in the form in which they are absorbed) and so cannot be used for energy.
Each food item has a specific metabolizable energy intake (MEI). This value can be approximated by multiplying the total amount of energy associated with a food item by 85%, which is the typical amount of energy actually obtained by a human after respiration has been completed. In animal nutrition where energy is a critical element of the economics of meat production, a specific metabolizable energy may be determined for each component (protein, fat, etc.) of each ingredient of the feed.
The conversion efficiency of energy from respiration into mechanical (physical) power depends on the type of food and on the type of physical energy usage.
Exertion while walking, running and playing makes us feel tired and less energetic. This is mainly due to loss of energy and sweat. Sweat contains a mix of water and electrolytes (salts) such as sodium, potassium, calcium, magnesium and chloride. Unfortunately by drinking water alone we do not replace salts and energy but only decrease our sensation of thirst while stimulating urine production.
Drinking a well-balanced mix of water, glucose, sucrose and salts enable us to replace sweat and restore energy. By drinking EnerzaL, a balanced energy drink, we facilitate rehydration by restoring water, energy and salts.