Calories, What They Are and What to Know
Calories, Whether Counted or Burned, Matter for Nutritional Health
Jun 22, 2009
Food eaten by animals contains calories. The calories in food are processed and captured by specialized enzymes inside living cells and organisms.
Enzymes are protein catalysts. Catalysts are special chemicals or biochemicals that speed up reactions. Catalysts are not used up in the reaction. Each different enzyme reacts with a specific food molecule (substrate) and causes thousands of the same reaction each second as long as the substrate is there and conditions remain suitable.
Enzymes change and re-arrange food molecules, release energy, and make new molecules needed by the organism’s cells and tissues. An understanding of food, molecules, enzymes, heat energy, and calories provides insights into diets and dieting.
Food Groups, Molecules and Energy, Calories and Calorimeters
Energy is defined as the ability to do work. Electrical and chemical energies are two important kinds of energy. Chemical energy is contained within the bonds of a compound.The bonds hold the atoms one to another, and when the bonds are broken, energy can be released. As the different enzymes break bonds and re-arrange molecules, they can trap, save and transfer energy. Some basic enzyme activities are listed below.
- Proteases, hydrolyze proteins to amino acids.
- Lipases, hydrolyze fats to glycerol + fatty acids.
- Carbohydrases, change starches and polysaccharides to monosaccharides, such as glucose and fructose which can be processed further to release energy.
- ATPases, generate storable and usable chemical ATP energy from trapped energy + ADP + phosphate.
The complete burning or oxidation of chemical compounds allows a determination of the heat content to be made. The total heat energy of particular compounds, such as carbohydrates or fats, can be determined by use of a calorimeter — a device to measure heat bond chemical energy. A food can be weighed, burned and the calories measured as total heat released. This burning can be likened to an ignited log, i.e. wood or cellulose, releasing heat, carbon dioxide and water. These three main end products of oxidation or combustion are produced from all organic matter.
Calories Defined and Things to Know About Food Energy
The caloric content of food is well known. A calorie is the amount of heat needed to raise the temperature of 1 gram (= 1 milliliter = ml) of water by 1 Centigrade degree. The large Calorie is the kilocalorie. Scientists and nutritionists measure the number of kilocalories available and released from food. Each kilocalorie or large Calorie is 1000X greater in heat content than a small calorie. One Calorie,therefore, is the amount of heat needed to raise the temperature of 1000 ml = 1 liter (L) = 1000 grams, by 1 Centigrade degree. When food is burned, energy is released and measurable as Calories per food gram:
- Carbohydrates, (sugars, starches, polysaccharides): 4 Calories/gram
- Proteins, (amino acids): 4 Calories/gram
- Lipids (saturated and unsaturated, fats= glycerol + fatty acids): 9 Calories/gram
Food Energy and Diets Made Clear and Simple
The basics for understanding food and energy now are in place. Anyone can determine the caloric content of food based on the percent composition of fat, protein and carbohydrate in each food. This determination is simplified in many food establishments that will provide customers with a list of the caloric amounts for the standard food items served. Further, all packaged and canned foods contain this caloric information on the container. A first step to becoming diet conscious and diet-wise is to know where and what the Calories are.
Read a Scientific Inquiry about logical diets, Mediterranean diets, basic diets and how they work.
Eating wisely can contribute to health and longevity. Be food- and calorie-wise. Start today.
Careers in nutrition and dietetics are rewarding, allied health fields.
Sources
Shapiro, H. M. Picture Perfect Weight Loss. 2000. Warner Books Inc., New York, N.Y. 343 pp
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