What are carbohydrates?
Carbohydrates are better known simply as sugars, and are divided into two categories according to their chemical formulae:
-simple sugars are composed of either one type of molecule (glucose, fructose and galactose) or two types (sucrose, maltose and lactose).
-complex carbohydrates are starch-based molecules composed of several hundreds of glucose molecules.
For a long time, the two types of carbs were seen as opposites: simple sugars which cause blood sugar to peak, and complex carbs which are absorbed slowly into the bloodstream. However, a new way of thinking has overturned this in recent years. We're talking GI, or glycaemix index. GI measures the speed at which carbohydrates are broken down and absorbed by the body, ie how high they raise your blood sugar levels. Glucose is the highest in the index, with a GI of 100. The higher the GI, the 'quicker' the carbohydrate; the lower the Gi, the 'slower' it is. Carbohydrates are the only nutrients that alter our blood sugar level when metabolised, and they're the only nutrients that can have a glycaemix index. Whatever the GI and sugar type, 1g carbohydrate = 4 kcal.
What do carbohydrates do?
Carbs are the essential fuel for the body and brain. Our muscles and liver are capable of stocking glucose (as glycogen), but only in small quantities. If you don't eat, the reserves in your liver will soon run out, and the reserves in your muscles will disappear in less than 24 hours. Without energy, your body has to break down protein (ie muscle) or fat reserves to get the energy it needs. Carbs provide the body with lasting energy, play a vital role in suppressing your appetite, give you energy and keep your mood up. If you want to lose weight, you shouldn't cut them out. Carbs aid your physical and mental capabilities and it goes without saying that they're vital for kids, students and athletes.
Sources of carbohydrate
Simple sugars are found in all sweet foods: sucrose and sweet foods (honey, jam, sugar, chocolate, biscuits, sweets and sweet drinks), fruit, green vegetables and dairy produce (except cheese). 100ml milk contains 4.6g carbohydrate, 100g apple contains 12g, 100g milk chocolate contains 50g and 100g jam contains 68g. Complex carbs are mainly found in grains, cereals, pulses and starch. 100g bread contains 44g carbohydrate, 100g rice contains 26g and 100g cooked lentils contains 13g. Many foods, such as biscuits and cakes, contain both types of carbphydrate, for example 100g cookies (57g carbohydrate), 100g rice pudding (20g) and 100g cake (47g).
How much carbohydrate do we need?
Carbs should make up 50-55% of our total daily calorie intake. We should take as many of them as possible from complex carbs and as little as possible from simple sugars.
Experts and official bodies agree that sugar is a major factor in weight gain. Sugars with a high glycaemix index are quickly absorbed by the body and easily stored as fat. They trigger a peak and then a sharp drop in insulin in the blood, bringing about sugar highs then lows, spells of fatigue and hunger. Carbs with a low GI help stabilise our weight because they don't bring about highs and lows in blood sugar, and they keep our appetite steady. We should aim to eat carbohydrates at every meal, choosing them with care! For breakfast, high-fibre bread, sugarfree cereal such as muesli with no added sugar, dairy produce and fruit are ideal; and at lunch and dinner, vegetable crudités, pulses, al dente or wholegrain pasta, rice, potatoes with the skin on, green vegetables, bread and fresh fruit are best. Try and limit your intake of very sugary foods like sweets, sugar and fizzy drinks.