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

functioning of the body. 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 Breakfast raises blood sugar and energy levels, Make sure you eat breakfast. which improves mental and physical performance. It counteracts the natural slow-down in Eat a high carbohydrate fibre metabolism and lowering of blood sugar levels snack mid-morning. that occurs by noon. Energy levels naturally drop around the middle of the day; eating lunch helps to keep your energy Always eat lunch. and stamina going. Eat regularly. Don't have a It prevents a dip in blood sugar levels and gap of more than four hours carbohydrate stores, so you keep your energy between meals. levels and stamina up. Avoid high fat foods (such as Fats take longer to digest than carbohydrates; crisps) before doing anything they stay in your stomach for longer and can make active. 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 Climbing stairs Cooking Cycling Dancing Dressing/undressing Eating a meal Football Gymnastics Horse-riding Netball Playing a musical instrument Reading Roller-skating

Energy (kilojoules) 280 85 212 162 85 51 196 153 144 178 85 38 246

Energy (calories) 67 20 50 39 20 12 47 36 34 42 20 9 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.


There are 7 kinds of nutrients;

Carbohydrates, Fats, Vitamins, Proteins, Minerals, Water, Fibre. These nutrients are needed for: Carbohydrates  Provide a quick source of energy  Fuel for muscles during exercise  Converted to fat if eaten in excess F a ts  Fuel when resting  Fats/oils an essential for good health 2 TYPES: Saturated Fats & Unsaturated Fats.  SATURATED: these are found in animal products and can be harmful to health if they are consumed in large quantities e.g. meats, dairy products, cakes, pastries and confectionary.  UNSATURATED: these are less harmful and many foods in this category can help promote the consumption of essential fats e.g. oily fish, pumpkin seeds, walnuts and dark green leafy vegetables. Proteins  A major part of the body – cells, skin, muscles and hair,  Not an energy provider  Can not be stored. Vitamins  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

Minerals  Growth,  Regulate body processes.  Sodium – regulates body fluids  Iron – Helps blood carry oxygen  Calcium – Bones and teeth Water  Most essential – 60% of body weight  Provides moisture for living tissue  Helps chemical reactions  Stops of dehydration  No calories Fibre  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

notes about nutrition  
notes about nutrition  

nutrition and exercise