KS3 Design and Technology / Biology: The science behind carbohydrates

STEFAN GATES:
OK, it's carb time, people, and these are big nutritional news, because a healthy diet is supposed to get 55% of its calories from carbohydrates. Now, I know what you're thinking. These are just big, empty words - calories, carbohydrates, nutrition. Show me something mind-blowing! So, that's my challenge - I'm going to make carbs interesting. Come down here, have a little look around, because all of these foods are packed full of carbohydrates, and some of them are brilliant to have in your diet. Let's hear from a sports star whose carbs are absolutely crucial.

JORDANNE WHILEY
My name is Jordanne Whiley and I'm a Paralympic wheelchair tennis player. I won a bronze medal at the Paralympic Games in London, I recently won all four Grand Slams this year, which is actually a record. Food's really important, because if I don't eat the right things, then I'm not going to be able to perform. And essentially, it's my life, so…and food plays a percentage in that, because if I go on court not eating anything, I'm not going to be able to perform to my best. During the day, I eat quite a lot of carbs, because it gives me a lot of energy, so training or matches, doesn't really matter, I'll still be eating a lot of carbs, which is normally quite a lot of pasta. I train Monday to Friday, four hours a day on court, and then three times a week in the gym. I wouldn't be surprised if Andy Murray did exactly the same. My grub does require a lot of energy. I could be on court for an hour to three and a half hours is, I think, the most I've ever played, and we can't stop the match halfway through just go and have a bite to eat, so we have to have enough food inside us to last as long as we need it to last, and we'll take on something that's got a bit of sugar in it, for instant energy. It's very, very important, because if I don't eat the right things, essentially, I can't finish my job, erm, then it's not good!

STEFAN GATES:
Jordanne needs a huge supply of energy. Now, we get energy from three main things in our food - fat, protein and carbohydrates. Now, fat and protein are all well and good, but they often come from foods that we shouldn't eat too much of. Carbs usually come from foods that offer loads of other great nutrition as well as the energy. Now, there are two main types of carbohydrates. First of all, you've got these fellas here, complex carbohydrates. Things like whole grains, wholemeal bread, rice and potatoes, that kind of stuff. Now, they are called complex carbohydrates because we have to digest them and break them down into the component sugars that they're made of before we can use the energy from them. On the other hand, you've got simple carbohydrates. Now, these have got their sugars in pretty much ready-to-use form. It's stuff like chocolate and sweets and fizzy drinks, all that kind of stuff, loads of energy in them. But if you eat too many of these, you can be at risk of things like tooth decay, and eventually, further down the line, things like heart disease. So, if you can, it's better to try and get most of your carb calories from these complex ones. Complex or simple, no matter. If you eat too many carbohydrates and don't get moving to burn off their energy, you'll be overloaded with potential energy, which is a polite way of saying you will put on weight.

Now, I did promise I would make carbohydrates interesting and I haven't really done that yet. So, it's time to put on some safety specs and talk about calories. Now, calories, to me, have always seemed such a theoretical concept. I've always wanted to see them. So I'm going to show you them, using this. This is the sugar shotgun. It's a two-part sugar cannon. Now, the bottom bit here is basically a big pressurised container. What I've got is a bit of sugar with some yeast, and the yeast is feeding off the sugar and transforming the energy in that and releasing gas. Now, the gas is building up more and more inside the bottle until it's at a terrifying pressure. Yup, that's pretty strong! Then it's going to release that pressure up the barrel until it gets to this baby here. Up here in this cartridge is a very finely milled, powdered form of a simple sugar. So, all of its energy is ready to be released. What I'm going to do is release all that powder over some flames and see what happens, see if that energy can be transformed into a little bit of heat. Let's see if it'll work. Now, I'm working in controlled conditions here. Don't try this at home - or anywhere else, for that matter!

Three, two, one… And that, my friends, was just 50 calories of simple carbohydrates. It's your body, you can eat what you like. But if you want to achieve your maximum potential, you're best off getting over half your calories from carbohydrates, and as many of those as possible from complex carbs. And remember, there are enough calories in a cake to blow a hole in the wall! That makes carbohydrates a bit more interesting, doesn't it?