Healthy Diet

Noadswood Science, 2011

Healthy Diet

To understand the importance of a healthy diet

Monday, April 10, 2023

Energy

Where do we get our energy from, and what do we use it for?

Our energy is derived from food - whereas plants can produce their own energy from sunlight, we must consume food

This food is our raw material - needed to make new substances for: - energy (movement etc…) growth and repair health

Balanced

A balanced diet contains the different nutrients in the correct amounts, keeping us healthy

Certain foods are not necessarily 'bad' for us, but eating too much of them could be

Foods contain nutrients: these are substances which provide raw materials for the body (we need nutrients, along with fibre and water for a healthy diet)

There are seven different nutrients, and some foods are particular rich in certain nutrients…

Food Groups

What are the 7 food groups? Carbohydrates Fat Protein Vitamins Minerals Fibre Water

Essential?

Nutrients are found within different foods, and they all play important roles within the body

Nutrient How the body uses it Food sources it is contained in

Carbohydrate To provide energy Cereals; bread; pasta; potatoes (sugars and starch)

Protein For growth, making new cells and repair of our bodies

Fish; meat; eggs; dairy products

Fat To provide energy, as a store of energy & for insulation

Butter; oil; nuts

Minerals Needed in small amounts to maintain health

Salt; milk (calcium); liver (iron)

Vitamins Needed in small amounts to maintain health

Dairy foods; fruit; vegetables

Fibre To provide roughage to help keep food passing through the gut

Vegetables; bran; wholemeal bread

Water Needed by cells and for body fluids Fruit juice; milk; water(!)

Balanced

Different foods contain different substances - there is no one food that contains all the substances the body needs. Instead you must eat a wide variety of foods - balancing your diet

Different people need different amounts of food. You need more food if you are particularly active, are pregnant etc… (the amount of energy food contains is measured in kilojules (kJ) - if you are more active, your kJ intake needs to be greater )

If we eat too little food, we will use up our store of fat and become too thin. If we eat too much food, especially foods rich in sugar and fat, we will increase our store of fat and become too fat

Poor Diet

If you have too little of a particular nutrient, we say that you have a deficiency in that nutrient, e.g. fibre deficiency can lead to constipation

Mineral deficiencies - e.g. iron deficiency can lead to anaemia (too few red blood cells); iodine deficiency can lead to a swelling in the neck called a goitre

Vitamin deficiencies - e.g. vitamin A deficiency can cause blindness; vitamin C deficiency can cause scurvy (makes the gums bleed); and vitamin D deficiency can cause rickets (legs bow outwards in growing children)

Vitamins

Many deficiency diseases are caused by a lack of vitamins and minerals

In 1747 James Lind scientifically proved that eating fruits prevented scurvy: - He took 12 men suffering from scurvy He gave them different treatments He found those given fruits (such as lemons) were cured of

the disease

In 1795 the British Navy started giving lemons (or their juice) to sailors

Metabolic Rate

A healthy diet contains all the different nutrients in the correct amounts, and provides the right amount of energy for each individual

An unbalanced diet can lead to a person becoming malnourished – they may be too thin or too fat as a result, and they may suffer from deficiency diseases

Respiration is the chemical reaction that allows cells to release energy from food – the metabolic rate is the speed at which such chemical reactions take place in the body

Metabolic Rate

Metabolic rate varies because of several factors, including: - Age Gender The proportion of muscle to fat in the body The amount of exercise and other physical activity Genetic traits

The metabolic rate increases as we exercise and stays high for a while afterwards

Basal Metabolic Rate

Metabolic rate is the rate at which your body burns calories

Basal metabolic rate (BMR) is the rate when resting

You can inherit a high BMR

You can also increase your BMR with more exercise (increasing your muscle to fat ratio)

Malnourishment

Malnourishment is a person with an unbalanced diet – these diseases are due to malnourishment: - Anaemia – lack of iron Obesity – too much fat Kwashiorkor – too much carbohydrate and no protein Anorexia – too little food

Recommended Daily Allowance (RDA)

RDA is the amount of a specific nutrient which is recommended for consumption per day – food packaging must clearly show this for each nutrient

A balanced diet should contain fats, proteins and carbohydrates in roughly these amounts: carbohydrates (red), fat (yellow) and protein (blue)

It should also contain minerals, vitamins, fibre and water

RDA

Food labels on products show the RDA of different nutrients within the food, usually per 100g and per serving of food…

Look at the food labels for a variety of foods and work out your average RDA % (are you having less than, the right amount, or more than what is recommended for a specific nutrient)?