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

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.

Proteins

Carbohydrates

Fats

Water

Vitamins

Minerals

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!

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

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 1800- 2400 calories/day A typical adolescent boy requires 2200- 3200 calories/day

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

Canada’s Food Guide