Lesson 2: Energy Giving Foods

=ENERGY GIVING FOODS=

INTRODUCTION
We have learnt in unit 1 that food is important to us because it makes us grow, it protects us and provides us with energy. We also learned that to be well nourished we should eat foods, which provide enough of the nutrients. In this unit we want to look at some of the nutrients that are so important to our bodies how we can get them and what happens to us if we do not get enough of them from food.

What are Nutrients?
Food contains nourishing substances called nutrients. Many nutrients have been identified and each has a specific job to do. Nutrients are divided into three classes. These are energy giving nutrients, protective nutrients and body building nutrients. The foods, which provide the energy nutrients called energy giving foods. The foods which provide protection nutrients are called protective foods and the foods which provide body building nutrients are called body building foods.

In this unit we would be learning mainly about energy giving nutrients and the foods which provide them.

Carbohydrates
They are one of the nutrients that provide our bodies with energy. They are the bodies most efficient fuel.Sugars and starches are the two main types of carbohydrates, starches are complex carbohydrates. They are complex because they are made of many glucose units. They are found in foods like rice, pasta, cassava, yam etc. when starchy foods are eaten and digested, simple sugars like glucose are obtained. It is this glucose that the body uses for energy.

Simple sugars
They can also be found in fruits, milk and grain products.They are also found in many For good health one should eat a lot of complex carbohydrates.Food source for complex carbohydrates include, beans, cereals and starchy vegetables.These foods would also supply other nutrients like vitamins and minerals. This makes them more useful than the simple sugars.


 * For the human brain to think and function it needs a steady, adequate supply of the simple sugar glucose.
 * The blood contains some amount of glucose and the rest is stored in the liver as glycogen. Glycogen is the bodies instance source of energy.  Glycogen is quickly converted into glucose to produce energy when it is needed.  For example during fright.  When the blood sugar level rises as a result of eating the body has a way of removing the excess glucose to bring the level to normal values.  If for some reason the body is unable to remove the excess sugar from the blood it accumulates and we say that the person had diabetes.

Fibre in the diet
The plant fibre eaten in food is called cellulose. Humans cannot digest fibre because they do not have the right enzymes to break the bonds in the fibre. Fibre however serves important functions in the body. For example it prevents constipation and lowers the energy value of food.

Importance of energy in the body
You have learned that the food you eat is turned into energy in the body. Now let us see what this energy is used for. Can you guess? Now read on

Energy obtained from food or from the body is used to maintain metabolism and to carry out physical activities metabolism is the chemical and physical processes occurring within the living cells of the body. Basal metabolism is the amount of energy needed by a body at rest to maintain the activities that support life. These activities include


 * Regulation of body temperature
 * Maintenance of breathing
 * Control of heartbeat
 * Breaking up molecules and building muscle tissue

Basal metabolism
It is measured by the basal metabolic rate. It is the rate at which energy is used by the body when it is resting after a 12hour fast.


 * Basal metabolic rate is affected by age, sex, temperature etc. The energy needs of an individual are determined by his or her basal metabolic rate and the kind of activity he/she indulges in.  for growing children the energy needs is also determined by growth rate.

Now that you have learnt about the importance of energy in the body let us look at another energy giving nutrient – fats and oils. **Fats and oils are in a family of substances called lipids and they are naturally presenting many foods.


 * They are not soluble in water.
 * They are made up of fatty acids and glycerol


 * Fats are different from oils in that fats are solids at room temperature whiles oils are liquids at the same temperature.


 * Fats are used to provide energy for the body. In fact most of the energy used by the heart is obtained from fats.


 * The body consumes fats in many forms. For most people fat is consumed as visible fats like margarine cooking oil, palm oil coconut oil groundnut oils sheabutter etc.  fat eaten may also be invisible as in milk, egg, cereals.


 * Apart from providing energy, fat performs many other functions in the body like protecting various organs keeping body temperature constand and keeping our hair glossy and healthy.


 * One of the greatest concerns today is the effect of fat on the heart. Too much fat in the diet is believed to contribute to heart problems.  Fats obtained from marine fishes are considered nutritious because they have high levels of omega 3 fatty acids which help prevent heart diseases.

16:34 February,26 2007.