DR CHRIS VAN TULLEKEN:We need energy every minute of every day to stay alive, not just when we're exercising. Now, we all know that our energy comes from our food and our drink but how does it get into them in the first place? Well, in the next clip I dig up some answers.
DR CHRIS VAN TULLEKEN:I love the countryside and farms, but in that romantic, slightly idiotic way that people, who live only in the city, do. As a reflection of how little I know, I have never dug up a potato which is what I am surrounded by here. But it can't be that hard, can it? I'm gonna eat my words.
DR CHRIS VAN TULLEKEN:Right, that's got it. Look at that. Lovely bunch of potatoes. Haven't done that particularly skilfully but nonetheless, here we have a potato, and look at this. I may not know much about farming, but I do know what's going on inside here. Look at that.
DR CHRIS VAN TULLEKEN:'It's potato starch. A carbohydrate. 'Our first main source of calories.' So this is about 150 calories. And in this field, there are about 500 million calories, and all of these potatoes are going to a crisp factory to be finely sliced and turned into crisps.
DR CHRIS VAN TULLEKEN:'Half a billion calories in a single field. 'It's mind-boggling. 'And all that energy comes from a source you might not expect. 'It's the sun.
DR CHRIS VAN TULLEKEN:'Take the apple trees in an orchard.' Every summer they do this amazing thing where they take sunlight and gas from the atmosphere and they turn it into calories, they turn it into sugar. So, they're locking up the sun's energy inside every apple.
DR CHRIS VAN TULLEKEN:I know I sound like some ludicrous apple advertisement but it's true that's what's happened in here. We've got sunlight energy locked up in an apple in the form of sugar.
DR CHRIS VAN TULLEKEN:'And that's true of all green plants. 'They take sunlight and turn it into calories. 'Even grass. 'Cows munch it all day long, 'and then almost magically transform it. 'into the second main source of calories in our food - fat.
DR CHRIS VAN TULLEKEN:'Milk is about four percent fat.' Cheers guys. 'Finally, most of us eat meat from the animals themselves, 'pig meat being a prime example.'
DR CHRIS VAN TULLEKEN:But whatever thing you're eating from a pig, whether it's a kidney a liver, or the bit we all love, the muscle, as you can see there, it's got protein in it. And protein is our third source of calories.
DR CHRIS VAN TULLEKEN:'So, in simple terms all the calories we eat come in just three types - 'Fat, protein, and carbohydrate, 'but each of these takes a wide variety of different forms.'
DR CHRIS VAN TULLEKEN:Well, thank you photosynthesis. And that's why our diets are so rich and varied. Eating carbs doesn't just mean potatoes and apples, but all the other fruits and vegetables as well, and breads, and pasta, and cereals.
DR CHRIS VAN TULLEKEN:The fats you need aren't just in milk, but in butter or cream, cheese, even chocolate.
DR CHRIS VAN TULLEKEN:Proteins are in all the different meats and fish, and of course if you're vegetarian you'll be getting your protein from things like nuts, seeds, pulses, eggs, tofu, and mycoprotein which, as everybody knows, is protein from fungi.
DR CHRIS VAN TULLEKEN:Makes me hungry just thinking about it.
Video summary
Dr Chris van Tulleken introduces the clip. He visits a farm and digs up a potato plant.
He explains that there are approximately 150 kilocalories in each potato, stored as starch.
But this energy has come from the sun, and he describes the process of photosynthesis.
Chris explains that the calories in our food are either in fat, protein or carbohydrates.
He summarises by listing some of the foods that are high in these three nutrients and explaining their role in a balanced diet.
This clip includes images of animal carcasses in an abattoir. Teacher review recommended prior to use in class.
Teacher Notes
Key Stage 2
Before watching the clip, ask students to write down some healthy foods that give us energy.
How does this energy get into the food chain? After the clip, ask students if they knew that energy was available in proteins as well as in carbohydrates and fats.
Key Stage 3
Before the clip, hand round some crisps and ask students to write a food chain which ends in ‘human’.
The correct answer is potato human. Can they do this for other healthy foods?
Ask students to explain where the energy comes from that is stored in the foods that they eat.
After the clip, ask students to name the three main nutrients that provide the energy in our diets.
This clip will be relevant for teaching Biology/Science at KS2 and KS3 in England Wales and Northern Ireland. Also at 2nd and 3rd Level in Scotland.
What is a calorie? video
Jem Stansfield explains what the term calorie actually means and then an explosion which releases the energy in breakfast cereal instantaneously.
What a human stomach looks like. video
Dr Chris van Tulleken has a close look at the human digestive system and explains what the different organs do during digestion.
Journey through the digestive system. video
Dr Michael Mosley swallows a tiny camera which travels through his digestive system.
