2. Unlimited Physical and Mental Energy.
The human body must produce large amounts of energy for all
physical and mental activities. With proper balance between health
and fitness, the body will have no trouble meeting the energy require-
ments for optimal human performance. But where does this energy
come from? The answer is both simple and complex. Basically, ener-
gy comes from the sun. Light energy from the sun comes to earth and
is converted to chemical energy in plants through the process of pho-
tosynthesis. We eat the plants, and most of us eat animals that eat
plants. The chemical energy we take in is converted to mechanical
energy that fuels all our physical and mental activities.
More directly, the energy produced by the body comes from the
foods we eat. This energy is obtained from the basic macronutrients
in food — carbohydrate, fat and protein. Though many foods contain
all three, there’s usually a predominance of one of these in each food.
Consider the following examples:
- Carbohydrates are predominant in bread, sugar, rice,
pasta, fruit and fruit juice, cereal. - Fats are dominant in oil, butter, cheese, egg yolk.
- Protein is highest in meat, fish, poultry, eggs, cheese.
The majority of energy is produced from two of these food groups
— carbohydrate and fat. Only a small amount, up to 15 percent of
total energy, is produced from protein (by conversion of certain amino
acids into glucose).
All three macronutrients are converted into energy in two steps.
First, they are broken down in the intestine and absorbed into the
blood as glucose from carbohydrates, fatty acids from fats, and amino
acids from protein.