Why do we need food?

Salad plate
The current healthy eating messages produced by the Government require some knowledge about food and nutrition.
The information below is designed to give you a basic introduction to nutrition and health.

Our bodies need regular intakes of food for the following reasons:

  1. To produce energy to allow us to breathe, think and move
  2. To grow/reproduce
  3. To carry out repairs (e.g. to heal a cut on your arm or a broken bone)

The major components of food that allow our bodies to carry out these functions are called nutrients.

Food nutrients

The food we eat is made up of three major kinds of nutrients:

  • Protein
  • Fat
  • Carbohydrate

These three nutrients all provide the body with energy (in the form of calories).

Food also supplies the body with vitamins and minerals (these are often referred to as micro-nutrients, because they are required in much smaller amounts).

A healthy balanced diet will provide the body with all the nutrients it needs to function correctly.

A calorie is a unit used to measure energy.

In terms of weight management it usually refers to either the energy we take in from food and drink or the energy we use up through keeping our body working or being physically active.

All weight loss programmes aim to shift the energy balance so that the energy going in is less than the energy going out. We can do this by:

  1. Changing the types and amount of food and drink we consume; e.g. swapping a glass or fruit juice to water will save about 200 calories per day.
  2. Increasing the amount of energy we use up e.g. for a man or woman weight 90kg, walking 30 minutes will use about 235 calories.
However, doing both at the same time is the best way to lose weight and keep it off for good.

Fat has a very high energy value (1g fat provides 9 calories, compared to 1g of carbohydrate which only provides 4 calories). Any fat in the diet not converted into energy is simply laid down in the body's fat stores. This is reason we advise people to follow a low fat diet, this will be discussed in more detail in later sections of the website.

There has been a great deal of media attention regarding the different types of fat.

Fats are divided into 2 categories:

Saturated fat:

found in animal products (such as butter, cream, cheese, meats). Saturated fat is also found in vegetable oils such as palm oil and coconut oil. These fats have been found to cause increases in cholesterol levels and increase your risk of developing heart disease.

Unsaturated fat:

found in plants and fish (such as olive oil and oily fish such as mackerel and herring). These fats are less damaging to the body, and eating a diet high in the fats found in oily fish is protective against heart disease.

Carbohydrates are the body's main source of energy. Carbohydrates are divided into refined and unrefined.

White bread

Refined carbohydrates refer to foods that have been altered by processing, so that the fibre containing parts (the bran and the germ) have been removed. Examples of refined carbohydrates are white bread, sugary cereals, pasta and noodles made from white flour.

Wholemeal Bread

Unrefined carbohydrates consist of the whole grain (the bran and the germ) and so are higher in fibre than unrefined sources. These foods make you feel fuller for longer. Examples include wholegrain rice, wholemeal bread and porridge oats.

Not all carbohydrates are equal, they are broken down, absorbed by the body at different rates and have different effects on your blood sugar level. This is also known as the glycaemic index of a food.

Foods with a low glycaemic index are thought to have health benefits for people with diabetes.

White sugar

Foods with a high glycaemic index are broken down more quickly and cause a rapid rise in blood sugar. Examples of high glycaemic index foods are white bread, sugar, sweets, sugary drinks and boiled white potatoes.


Foods with a low glycaemic index are broken down more slowly and cause slower rise in blood sugar. Examples of low glycaemic index foods are pasta, sweet potatoes, basmati rice, pulses, beans, nuts, lentils, wholegrain cereals, vegetables, fruit (such as apples, apricots, peaches and pears).

The glycaemic index of a food depends upon a number of factors, such as food processing and cooking, so you can't determine a foods glycaemic index just by looking at it.

Unrefined carbohydrates tend to have a lower glycaemic index, so try to incorporate these foods into your diet.


Proteins are the building blocks of the human body, our skin, hair, nails, muscles and bones are all made up of proteins.

We need to provide our bodies with proteins so that muscles can be repaired and muscles can develop.

The best sources of protein in the diet are meat, fish, eggs, milk and other dairy products.

Black-Eued Beans

Plant-based foods also provide the body with a source of protein (such as beans, lentils and pulses) but you need to have a good mixture to provide the range of proteins you need.

These are needed by the body in small amounts for growth, development and to function efficiently. Below are the main vitamins and minerals and the best food sources of each.


Vitamin A:

The body needs this for skin development and repair, and for the development of good eyesight.

Sources: Eggs, fish oils, carrots, dark green or yellow vegetables

B Vitamins:

The body requires this group of vitamins for energy production and growth and repair.

Sources: found in a variety of sources - dairy products, wholegrain products, meat and fish

Folic acid is an important B vitamin, which is required for the production of red blood cells and help a baby develop properly during the early stages of pregnancy.

Sources: rich sources are fruit and vegetables
Fruit Bowl

Vitamin C:

This is required for healthy skin, bones, and muscles, for wound healing and for the development of good eyesight.

Sources: fruit and vegetables

Vitamin D:

This is required for healthy bones and teeth.

Sources: sunlight, also found in small amounts in dairy foods, eggs and oily fish.


This is required for healthy teeth and bones.

Sources: Dairy foods, leafy green vegetables, nuts, root vegetables, fish with bones (e.g. sardines)


This is required for the production of red blood cells and for a healthy immune system.

Sources: Red meat, oily fish, dark green vegetables, eggs, beans and pulses, dried fruit, cereal products.


This is required for wound healing and a healthy immune system.

Sources: red meat, dairy products.

This is the component of plant-based foods which cannot be broken down by the digestive system.

It adds bulk to foods and contributes to the "full feeling" after a meal.

It does not provide any nutrients but is essential for a healthy digestive system, it ensures regular bowel movements and prevents constipation.

It can also help lower high blood cholesterol levels.

There are two types of fibre; insoluble and soluble.

Wholemeal Bread

Insoluble fibre: helps your bowels pass food and prevents constipation. Sources: wholegrain and wholemeal products, pulses and oats.

Citruds Fruit

Soluble fibre: lowers cholesterol and controls blood sugar. Sources: apples, pears, citrus fruits, oats and barley.


Salt (also knows as sodium chloride) is required by the body for maintaining its water balance.

We only need very small amounts of salt (6g per day or 2.5g sodium) but most people in the UK are consuming 9g per day. Eating too much salt can raise blood pressure and this can increase the risk of strokes and heart disease.

The majority of the salt we eat comes from processed foods such as tinned or packet soups, and ready meals, so always check the food label to find those with less salt. The salt we add to food when cooking or at the table and the salt naturally found in foods also adds to our intake.

By following our healthy eating plan, the amount of salt you are eating will automatically be reduced, however below are a few tips on how to cut down your salt intake even more.

Tips on how to cut down your salt intake

  • Check food labels, and choose those with less salt added.
  • Cut down on salty snacks such as crisps/nuts and heavily salted foods such as bacon, cheese and other processed foods.
  • Taste your food before you add salt, you may not need it.
  • Avoid adding salt during cooking, use herbs and spices to flavour your food.
  • If you need to add salt during cooking, do not add it again at the table.

Obesity reduces life expectancy by on average nine years and causes 9000 premature deaths each year in England.

Managing your weight

The positive news is that even moderate amounts of weight loss can significantly improve your health. If you are overweight, losing 5-10% of your body weight can significantly reduce your risk of high blood pressure, diabetes and high cholesterol.