Diet & Nutrition

“You are what you eat” – some people say – that is how vital this subject is. “It is very important to know about different foods, what they contain, and why we need to eat them.”

What should I eat? You need to eat a balance of: Protein (15%) Carbohydrates (55%) Fats (30%) All these make up the bulk of your diet. You need these for energy. You also need vitamins and minerals.

Carbohydrates They are used as energy. Broken down in your gut to glucose. Some of this is stored as glycogen in your liver and muscles. Bananas, bread, cereals, rice and pasta.

Two types Simple Carbohydrates Found in sweets, jam and cakes. You should not eat much of these. Complex Carbohydrates Found in bread, pasta, rice and potatoes and cereals. These should be the biggest part of any meal.

Fats Fats are also used for energy. Muscles use a mixture of fats and glycogen. The mixture depends on how intense the exercise is, how long and how fit you are. The fitter you are the less glycogen is used. Butter, sunflower oil, nuts, red meats, hamburgers.

Protein Your body needs this to build cells, make blood and to restore and repair muscle and other tissue. You can also use it as energy only after the other two sources run out. Chicken, eggs, fish, beans and lentils.

Vitamins and Minerals You need tiny amounts of these. Vitamins A and D can be stored in your liver. Vitamin C can’t be stored. If you eat more than you need, it is excreted. You must eat it regularly.

Minerals They are just as important. There is enough iron inside you to make a large nail. Without iron your body can’t carry oxygen. Without calcium you’d have no bones, teeth or muscle contractions.

Vitamin A Found in fish, liver, vegetables, eggs, milk. You need it to see in dim light and for healthy skin. A shortage of this leads to night blindness and flaking skin.

Vitamin C Found in oranges and other citrus fruits, vegetables. You need it for healthy skin and gums and to help wounds heal. A shortage leads to scurvy.

Vitamin D It is made by the skin in sunshine and is found in milk, fish, liver and eggs. It gives you strong bones and teeth. You can’t absorb calcium without it. A lack of it can lead to rickets.

Calcium It is found in milk, cheese, dried fish, sardines, green vegetables. It gives you strong bones and teeth, and muscle contractions. A lack of this leads to osteoporosis (brittle bone disease)

Iron You find it in liver, beans, lentils, green vegetables and added to bread. It allows oxygen to be carried in your red blood cells. A shortage of iron leads to tiredness and anaemia.

Iodine It is found in sea food and vegetables grown near the sea. It is used by the body in the thyroid hormones that control the rate at which you burn up food for energy. A lack of it gives you a thyroid gland (goitre).

Water It does not give you energy but half your body weight is water. You could live for several weeks without food but only 4 or 5 days without water. You should drink at least 6-8 glasses a day. If you play sport you need more.

Fibre You find it in fruit vegetables, brown bread and other cereals. It is important because- it makes a bulky mass which the muscles in your gut can grip and push along quickly, it prevents constipation. It absorbs poisonous wastes from digested food. It makes you feel full, so you eat less.

Energy Needs

Your energy needs Even when you are relaxed and resting you need energy. You need it to keep warm; To keep your heart beating and lungs breathing; For all the reactions that go on in your cells.

Basal Metabolic Rate (BMR) It is the amount of energy you need just to stay alive, awake and comfortably warm.

Working Energy (WE) To move around, digest food and do exercise, you need even more energy. The amount of working energy your body requires depends on how active you are.

How to measure your energy needs It is calculated using the following equation: (Total Energy Needed = BMR + WE) It can be measured in kilojoules (kJ) or in kilocalories (C). 1 kilocalorie = 4.18 kilojoules.

Different people have different energy needs It depends upon: Your age – you need more energy now than when you were little. Your sex – males usually need more energy than females of the same age. Your lifestyle – the more active you are, the more energy you need.

How much energy do foods give Your body can use carbohydrates, fats and proteins for energy. Compare the energy each gives: 1g of carbohydrate = 17.1 kJ 1g of protein = 18.2 kJ 1g of fat = 38.9 kJ It is therefore easier to eat more fat than you need. If this happens you put on weight.

The Energy Balance If energy in is greater than energy out, the extra energy is stored as fat and you gain weight (Obese) If energy in = energy out your weight will not change. If energy in is less than energy out then the body will use up stored fat and you will lose weight. (Anorexic)

A Balanced Diet Eat plenty of fresh fruit and vegetables. They give you carbohydrates, fibre, vitamins and minerals. Eat starchy foods such as brown bread, pasta, potatoes and rice for carbohydrates and fibre. Eat fish, eggs and white meats for protein. But get at least some vegetable protein from beans, peas, nuts and lentils. Cut down on fatty foods. They make you fat and can cause heart disease and obesity. Beware of the hidden fats in chips, cakes, crisps and biscuits.

Cut down on sugar. It is pure carbohydrate Cut down on sugar. It is pure carbohydrate. It gives you energy but rots your teeth and is linked to heart disease. Cut down on salt. Doctors think it can cause high blood pressure. Cut down on processed food such as ‘ready to cook’ meals. In processing food, fibre and other goodness is removed. Sugar salt and chemicals called additives are added for flavour and colour. None of these are good for you. They can be harmful.

Weight Control and Fitness

Body Weight It depends upon: Your height and frame size – the longer and thicker your bones the more you will weigh; How much muscle and fat you have. (muscle weighs more than fat) Your sex – males are usually heavier than females.

Fitness and Body Composition If you are male, no more than 13–15% of your weight should be body fat. If it is more you are fat. Over 20% you are obese. Female = 18-20% of your weight should be fat. If it is over 30% you are obese.

Underweight You are underweight if you are below the normal weight range for your height. Exercise will make you feel weaker and more tired.

Anorexia Some people go on harsh diets to lose weight. This is very dangerous and can lead to anorexia. You do not eat enough carbohydrate, so your body uses stored fat for energy. It then runs out of fat and starts using proteins from body tissues. It can result in your organs to stop working properly. You may die.

How to lose weight Eat a healthy balanced diet, but eat less of it. Your muscles will grow when you exercise. Muscle weighs more than fat but takes up less space. You won’t lose much weight at first but you will look slimmer. Regular exercise.

Eating for sport Don’t eat more than you need. Carbohydrates will be the main source of energy. You will also use fats for energy depending upon how long the activity is. Intense exercise causes wear and tear to your muscles so you need proteins to repair the damage. Make sure you drink plenty of water during and after sport. A balanced diet will give you enough vitamins and minerals. You do not need supplements. In fact an excess of vitamins A and D can be dangerous.

Carbo-loading It is used by athletes for long events (2 or more hours). First cut down on carbohydrates and train hard. This uses up all your glycogen. Then eat lots of carbohydrates and train lightly in the days just before the event. Your muscles will now store more glycogen than usual.