Key Definitions Nutrient Are chemical substance in food that are essential for proper

functioning of the body.

Nutrition Is the science of nourishing the body properly. ENERGY FROM FOOD

Anything that moves needs energy, including the human body. It needs energy to work properly and stay healthy, as well as to do activities.

Food and drink gives your body the energy it needs for the important processes of life such as breathing or growing. But it also gives us energy for activities like walking, running or just talking. You use energy all the time. The more active you are, the more energy you use.

The body's energy needs

Whether a person is rushing around, or just taking it easy and relaxing, their body is using energy.

Different people need different amounts of energy, depending on their age, gender, size, health and how active they are. Some people live busy, active lives, exercise a lot and are rarely still except when they sleep. These people use a lot of energy so they need to eat more food to give them that energy. Other people are less active, preferring to read or watch tv, and need less food because they use less energy.

Energy through the day

The body has natural energy 'highs' and 'lows' during the day. This chart shows the energy levels for a typical 14 year-old.

The body needs enough food to keep it going during the day, and even out the energy highs and lows.

The best foods for giving energy contain carbohydrates. Find out more about different food groups and the importance of carbohydrates here. Bread and cereal contain carbohydrates, so that's why they are good for breakfast. ’Breakfast’ means that the meal breaks our night-long fast, giving the body the energy it needs to get going again.

Here’s how to keep your body topped up with energy through the day.

Planning tip Why it works

Make sure you eat breakfast. Breakfast raises blood sugar and energy levels, which improves mental and physical performance.

Eat a high carbohydrate fibre snack mid-morning.

It counteracts the natural slow-down in metabolism and lowering of blood sugar levels that occurs by noon.

Always eat lunch. Energy levels naturally drop around the middle of the day; eating lunch helps to keep your energy and stamina going.

Eat regularly. Don't have a gap of more than four hours between meals.

It prevents a dip in blood sugar levels and carbohydrate stores, so you keep your energy levels and stamina up.

Avoid high fat foods (such as crisps) before doing anything active.

Fats take longer to digest than carbohydrates; they stay in your stomach for longer and can make you feel heavy and sluggish while you exercise

Energy input and output

The amount of energy the body gets from food = energy input. The amount of energy the body uses up is = energy output.

The more food a person eats, the larger the input; the more active they are, the bigger the output. It is important the energy input and output is kept in balance.

If you eat too little, the body does not get the energy it needs and there is a negative energy balance. You may lose weight because the body uses up its fat reserves to provide the extra energy.

If you eat too much, more than is needed for the energy your body is using, there is a positive energy balance. Because you are not using up all the food you eat, you may put on weight.

Keeping your energy input and output in balance is not easy. Most people are not active enough. But you don’t have to be very sporty or enjoy the latest fitness fad – simple activities like walking instead of going in the car, climbing stairs instead of taking a lift or escalator, or helping to mow the lawn or do the housework are all ways of being active and keeping your input and output balanced.

Measuring energy

The energy provided by food or drink is usually measured in calories (or joules).

1 calorie = 4.2kJ (kilojoules)

Scientists find out how much energy there is in a particular food by burning a sample of it and measuring how much heat energy is released. The process is called calorimetry.

This chart shows the average energy used in 15 minutes by a child weighing 35kg (5½ stone) doing different activities.

Activity Energy (kilojoules) Energy (calories) Climbing stairs 280 67 Cooking 85 20 Cycling 212 50 Dancing 162 39 Dressing/undressing 85 20 Eating a meal 51 12 Football 196 47 Gymnastics 153 36 Horse-riding 144 34 Netball 178 42 Playing a musical instrument 85 20 Reading 38 9 Roller-skating 246 59

Calories in food

Food and drink provide the calories needed by the body. The table shows the average calories in some everyday foods. The actual number depends on the size of the portion – check the labels to see exactly how many calories they contain.

FACTORS AFFECTING PERFORMANCE DIET

There are 7 kinds of nutrients;

Carbohydrates, Fats, Vitamins, Proteins, Minerals, Water, Fibre.

These nutrients are needed for:

CCaarrbboohhyyddrraatteess

Provide a quick source of energy

Fuel for muscles during exercise

Converted to fat if eaten in excess

FFaattss

Fuel when resting

Fats/oils an essential for good health 2 TYPES: SSaattuurraatteedd FFaattss && UUnnssaattuurraatteedd FFaattss..

SSAATTUURRAATTEEDD:: tthheessee aarree ffoouunndd iinn aanniimmaall pprroodduuccttss aanndd ccaann bbee hhaarrmmffuull ttoo

hheeaalltthh iiff tthheeyy aarree ccoonnssuummeedd iinn llaarrggee qquuaannttiittiieess ee..gg.. mmeeaattss,, ddaaiirryy pprroodduuccttss,,

ccaakkeess,, ppaassttrriieess aanndd ccoonnffeeccttiioonnaarryy..

UUNNSSAATTUURRAATTEEDD:: tthheessee aarree lleessss hhaarrmmffuull aanndd mmaannyy ffooooddss iinn tthhiiss ccaatteeggoorryy

ccaann hheellpp pprroommoottee tthhee ccoonnssuummppttiioonn ooff eesssseennttiiaall ffaattss ee..gg.. ooiillyy ffiisshh,,

ppuummppkkiinn sseeeeddss,, wwaallnnuuttss aanndd ddaarrkk ggrreeeenn lleeaaffyy vveeggeettaabblleess..

PPrrootteeiinnss

A major part of the body – cells, skin, muscles and hair,

Not an energy provider

Can not be stored.

VViittaammiinnss

Essential in minute quantities

Protective substances – lack of illness, disease.

A - Eyes

B – Skin, Nails, Hair

C – Resistance to infection

D – Bones, Teeth

K – Blood clotting

MMiinneerraallss

Growth,

Regulate body processes.

Sodium – regulates body fluids

Iron – Helps blood carry oxygen

Calcium – Bones and teeth

WWaatteerr

Most essential – 60% of body weight

Provides moisture for living tissue

Helps chemical reactions

Stops of dehydration

No calories

FFiibbrree

Found in plant cells

Can not be digested,

Absorbs water – creates bulk in intestines

Lowers blood cholesterol.

A BALANCED DIET

60% Carbohydrates 25% Fat 15% Protein