Calories refers to the energy available in food. It is usually expressed as kcal (in Europe) and calories in US and Canada. Carbohydrates, fiber, fats, proteins, organic acids, polyols, and ethanol all release energy during respiration—this is often called 'food energy'. When nutrients react with oxygen in the cells of living things, energy is released. A small amount of energy is available through fermentation. Fats and ethanol have the greatest amount of food energy per mass, 9 and 7 kcal/g (38 and 30 kJ/g), respectively. Proteins and most carbohydrates have about 4 kilo calories per gram (17 kJ/g).
Importance of Calories
Human beings need energy to survive. The calories or energy in food is used for breathing, movement, pumping blood, all metabolic processes, and every physiological process in the body.
- Metabolic Processes
- By burning calories through metabolic processes, carbohydrates are broken down into glucose and other sugars, fats are broken down into glycerol and fatty acids and proteins are broken down into amino acids. These breakdown molecules are then transported through the bloodstream to the cells, where they are either absorbed for immediate use or sent on to the final stage of metabolism in which they are reacted with oxygen to release their stored energy.
- Weight Management
- A person's weight is strongly a reflection of the difference between the calories that they consume and the calories that they use. Calories are used through metabolic processes, exercise and other forms of activity.
- For many people, losing weight is based on either decreasing the daily calories that they consume, or increasing the daily calories that they burn.
- Overall Health
Recommended Daily Intake
The recommended daily intake is based on a person's age, weight, body composition, activity level and health status. Daily energy intake recommendations varies for each individual, but some general guidelines are as follows:
- Young adult men require between 2,500 and 2,700 kcal.
- Young adult women require between 1,900 and 2,200 kcal.
- Children and older people require fewer calories.
- Those that are sedentary require fewer calories; those that are physically active require more.
To determine your specific calorie needs ask your naturopathic doctor or check out the following guide from Health Canada .