Energy and Protein

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Energy

Energy is the most vital component of food intake and hunger is the stimulus to increase our energy intake.  Our requirements depend upon age and physical activity.  All foods provide energy but their content may vary widely and our choices of energy source can have profound effects upon our intake of micronutrients (vitamins and minerals) as well as our health.
Energy in food is measured as kilocalories (kcal), which in common use is often abbreviated, incorrectly, to calories (one thousandth of a kilocalorie). 
The alternative measure for energy is kilojoules with 4.184 kJ = 1.0 kcal.

Adult Requirements and Intakes

Content of Individual Foods

Protein

Protein is an essential macronutrient that provides component amino acids that are released during the process of digestion.  Some amino acids that the body requires cannot be manufactured and thus it is essential that we eat protein-rich foods in order to obtain them.  Proteins can be provided by both animal as well as vegetarian sources but vegetarians will need to eat from a variety of sources to obtain all of the essential amino acids whereas animal sources are normally complete.  There is a daily requirement for protein which is increased during periods of growth and illness.  As a rule protein-rich foods are also rich in other nutrients and are thus a sought-after component in most people’s diets.
Any excess of protein can be used as an energy source or converted into and stored as fat. 

Adult Requirements and Intakes

None or minimal amounts are provided by nutritional supplements unless a specific high-protein food supplement is being taken.

Content of Individual Foods

Main page | Energy & Protein | Vitamins | Minerals | Essential Fatty Acids