nutrition - the study of the nutrients in foods and in the body.
diet - the foods and beverages a person usually eats and drinks.
nutrients - components of food that are indispensable to the body's functioning. They provide energy, serve as building material, help maintain or repair body parts, and support growth. The nutrients include water, carbohydrate, fat, protein, vitamins, and minerals.
energy - the capacity to do work. The energy in food is chemical energy; it can be converted to mechanical, electrical, thermal, or other forms of energy in the body. Food energy is measured in calories.
calories - units of energy. In nutrition science, the unit used to measure the energy is a kilocalorie (kcal or Calorie): it is the amount of heat energy necessary to raise the temperature of a kilogram of water 1 degree Celsius.
metabolism - the sum of all physical and chemical changes taking place in living cells; includes all reactions by which the body obtains and spends the energy from food.
carbohydrates - compounds composed of single or multiple sugars. The name means "carbon and water" and a chemical shorthand for carbohydrate is CHO, signifying carbon, hydrogen, and oxygen.
complex carbohydrates - long chains of sugar units arranged to form starch or fiber; also called polysaccharides.
sugars - simple carbohydrates.
glucose - a single sugar used by plant and animal tissues for energy.
starch - a plant polysaccharide composed of glucose; a plant's storage form of glucose. After cooking starch, it is highly digestible by the human body; raw starch often resists digestion.
fats - lipids that are solid at room temperature. protein - compounds composed of carbon, hydrogen, oxygen and nitrogen and arranged as strands of amino acids. Some amino acids contain the element sulfur.
amino acids - the building blocks of protein.
essential amino acids - amino acids that either cannot be synthesized at all by the body or cannot be synthesized in amounts sufficient enough to meet physiological need. They must be ingested.
- The energy of a carbohydrate molecule is 4 cal/g.
- The energy of a protein molecule is 4 cal/g.
- The energy of a fat molecule is 9 cal/g.
- The energy of an alcohol molecule is 7 cal/g.