1. Energy in different foods
2. Getting oxygen and glucose to your cells
3. Measuring the process of respiration
4. Balancing energy intake and output

‘Energy for life’ examines the process of respiration. We begin by investigating the energy content of different foods through the example of an Antarctic voyager. Oxygen is needed to release energy from food. We see food being burnt in liquid oxygen and a calorimeter is used to measure the energy in different foods.

The lungs and circulatory system are responsible for getting oxygen to all body cells. A 3D graphic animation illustrates the process. The oxygen meets glucose in a cell and we see the process summarised as a word equation. The work of a paramedic team is used to illustrate the importance of oxygen and glucose to the body.

The efficiency of the body in carrying out respiration is a measure of fitness. Ade Adepitan, a paralympic basketball player, goes through a series of tests to measure changes in his breathing and respiration with exercise. Our 3D graphic shows how waste carbon dioxide leaves Ade’s body.

Different people need to take in different amounts of energy. We look at a variety of individuals and lifestyles to pick out the important factors. If we eat too much food we put on weight. We visit a weight-loss camp to find out how diet and exercise are monitored to encourage young people to balance their energy intake and output.

If we eat too little we can lose weight. The effects of famine and the dangers of the psychological illness anorexia nervosa are examined.

00.23 What food should you take if you’re going to cross the Antarctic?
The Antarctic is one of the most isolated and inhospitable places in the world. We meet Susan who plans to be the first British woman to cross the Antarctic on her own. She is training herself to pull a 180kg sled by pulling tractor tyres around a field. As well as essentials like navigation and communication equipment, a medical kit and warm clothing, Susan has to carry a three-month supply of food.

02.15 Susan has worked out how much energy she needs to take in from her food. She explains how many calories of energy are needed to keep her body going, to pull her sled and to keep warm. It all adds up to 6000 calories or 24,700 kilojoules. She needs lightweight, high-energy foods. What should she take?

03.22 How can we get the energy out of food?
The energy in food is locked up in chemical bonds. To release this stored energy we use oxygen. If a cracker is soaked in liquid oxygen it burns very violently.

03.57 Which foods contain most energy?
Peanuts contain lots of fat. Dried potato contains lots of carbohydrate. We can find out which contains most chemical energy by using a calorimeter. Using a glass calorimeter, we see how the food is ignited using a coil and burns rapidly in oxygen. The food burns completely and almost all the energy released is absorbed by a surrounding jacket of water.

We watch the temperature of the water change as one gram of peanuts and one gram of dried potato are burnt. A quick calculation converts the temperature change into energy released. The peanuts contain a lot more energy because they are rich in fat. Fats contain almost twice as much energy per gram as carbohydrate.

05.30 What will Susan take?
Susan shows the kind of food that she would normally eat to get 24, 700 kilojoules of energy. It looks nice but it’s far too heavy. An easily manageable lump of lard would give the same amount of energy, but it's not too appetising! In reality Susan will take a range of high fat foods, many of which are dried.

06.26 Why is glucose so important?
When we digest food some of it is turned into glucose. Glucose is the body’s main source of energy. Susan will top up her glucose levels with high-energy isotonic drinks and biscuits.

Susan will be taking expedition foods that make up proper meals. Although they are heavier they will make her feel better.

07.24 How does oxygen get to your cells?
In Antarctica, oxygen is plentiful, but sometimes we have to take our own supply with us. We see a montage of shots including a submarine, high altitude climbing, a scuba diver, a fighter pilot and astronauts.

We watch oxygen enter the body in a 3D graphic animation. The oxygen passes into the blood where glucose is carried by the plasma. When the blood reaches the capillaries, oxygen and glucose diffuse into body cells. A close up of a single cell shows the oxygen and glucose combining explosively. The process is summarised on screen as a word equation.

08.20 How can oxygen and glucose save a life?
The West Yorkshire Metropolitan Ambulance Service train paramedics to deal with casualties at the scene of an accident. We follow a training exercise involving a car accident. The first thing to check is that a supply of oxygen is getting to the casualty. Only then do the paramedics check for injuries.

This casualty is diabetic. A diabetic cannot control the amount of glucose in the blood. Because the level of glucose in the blood is low, a shot of glucose is given directly into the bloodstream.

All living things need to release energy from glucose. We see a montage of shots including a wide variety of animals and plants.

09.36 How can we use respiration to measure fitness?
Ade Adepitan is a top wheelchair basketball player who was in the British paralympic team at the Sydney Paralympic Games. Ade runs through his vital statistics for a basketball game - how many times his heart beats, how many times he breathes, how much air this represents and how many kilojoules of energy he will use.

The air that Ade breathes in and out is compared. We see results for the volume of air he breathes and proportions of oxygen and carbon dioxide that he breathes out. The measurements are taken at rest, during sub-maximal exercise and at his maximum level of exercise. As Ade works harder, the figures show an increase in the volume of air breathed in, the amount of oxygen absorbed and the amount of carbon dioxide given out.

12.38 How do cells get rid of carbon dioxide and water?
We return to the same 3D graphic animation to see carbon dioxide and water passing into the blood. Carbon dioxide diffuses into the lungs and leaves the body. Some water is lost from the lungs but much of the water made in respiration will be used for other purposes. These measurements will give a picture of how fit Ade is.

All these measurements show that Ade is releasing more energy when he exercises. A direct way of measuring this is to use a thermal imaging camera. We see how more heat is lost from Ade’s body as he exercises.

13.11 How much energy do we need?
As athletes, Ade and Susan will use a lot of energy. But what about everybody else? A line-up of different types of people indicates that the amount of energy we need each day depends on body mass, age, gender, lifestyle, and pregnancy.

14.59 What happens when we eat too much?
A set of scales shows the need to balance energy input and energy output. We visit Leeds Metropolitan University where Marc attended a weight-loss camp. He explains how he learnt the need to balance his energy intake and output. Paul Gately explains how the camp helps young people to monitor their food intake and take regular exercise. He outlines the statistics for obesity amongst young people and the associated health risks. Marc explains some of the difficulties that young people have in maintaining a healthy lifestyle.

17.01 What happens when we don’t eat enough?
In this country we have access to a wide variety of foods. Some people are not as fortunate. In a famine, lack of high-energy food leads to weight loss and exhaustion. Eventually the body wastes away as muscle is broken down for energy.

We see examples of how magazines and other media encourage dieting to lose weight. But excessive dieting and the anxiety associated with it can lead to serious illness. Anorexia nervosa is a psychological illness which results in weight loss and can lead to death.