1. Nutrition
Nutrition involves all the processes involved in the absorption, use and elimination of the substances needed to keep our bodies in good working order.
This involves:
1) The digestive system: needed to transform the food we eat into nutrients our cells can use
2) The respiratory system: oxygen is needed to transform the nutrients we eat into chemical energy
3) The cardiovascular system: our blood circulates the nutrients and oxygen to our cells.
4) The urinary system: needed to filter our blood and eliminate waste in liquid form

2. Essential Nutrients
To function, the human body must have nutrients. The nutrients known to be essential for human beings are:
1) proteins
2) carbohydrates
3) fats
4) water
5) vitamins
6) minerals
A nutrient is a substance found in food that is used by the body to meet important needs.

3. Proteins

4. Carbohydrates

5. Fats

6. Water

7. Vitamins

8. Minerals

9. The Energy Value of Food
A joule (J) is the typical measurement unit for energy
With food, however, calorie (cal) is commonly used to measure the energy content of foods.
1 cal = ~ 4000 J or 4 kJ (kilojoules)
Energy is used for everything we do, from breathing to talking and even sleeping!

10. Energy Output for Various Activities
Activity (1 hour)
Required Calories
Sleeping or resting 60
Sitting 90
Standing
120
Walking
170
Running
Over 300

11. Energy Requirements
The amount of energy you need to perform your daily activities determines the amount of food you should eat.
This is different for every person depending on:
Age
Sex
Weight
Level of physical activity
A typical adolescent girl requires calories/day
A typical adolescent boy requires calories/day

12. Energy Value
Carbohydrates and fats are the body’s major source of energy
Proteins are mostly used to build and repair body tissue, but may be sometimes used as an energy source if there are not enough carbohydrates or fats to meet our energy needs.
Water, vitamins and minerals are NOT sources of energy

13. Canada’s Food Guide