Asked by: Roger Britton, via email
The sugar in fruit is mostly fructose and glucose. Glucose is the primary food molecule, and can be used directly by the cells in your body. Fructose, however, must be converted into glucose before it can be used. This happens in the liver, but there is a limit as to how fast the liver can process fructose. When it is overloaded, it will instead convert the fructose into fat – so high-fructose diets tend to make you obese.
But surprisingly, a diet that’s rich in fresh fruit isn’t a high-fructose diet! That’s because fruits have a lot of fibre and water that slow down your digestion and make you feel full. In fact, research has found that apples and oranges are some of the most filling foods per calorie – higher than steak or eggs. So although a medium apple contains 19g of sugar, including 11g of fructose, you will feel less hungry afterwards than if you had the same amount of sugar from a fizzy drink (roughly half a can of Coke).
It is almost impossible to get too much sugar from fresh fruit, but this doesn’t apply to fruit juice or dried fruit. They are much easier to binge on.
Subscribe to BBC Focus magazine for fascinating new Q&As every month and follow @sciencefocusQA on Twitter for your daily dose of fun facts.
