ishouldcocoa so glad it's not just my DS!
I found this on the NHS website.
Teenagers need lots of energy and nutrients because they’re still growing. The amount of energy that food and drink contains is measured in both kilojoules (kJ) and kilocalories (kcal) commonly just referred to as calories.
A report from 2011 estimated that the average energy requirements for children aged 13-18 years old a day is:
Age (years) Boys Girls
13 10,100kJ /2414kcal 9,300kJ /2223kcal
14 11,000kJ /2629kcal 9,800kJ /2342kcal
15 11,800kJ /2820kcal 10,000kJ /2390kcal
16 12,400kJ /2964kcal 10,100kJ /2414kcal
17 12,900kJ /3083kcal 10,300kJ /2462kcal
18 13,200kJ /3155kcal 10,300kJ /2462kcal
However, these figures are only a guide. Young people might need more or less energy depending on a number of factors, including how physically active they are.
But frankly, I can't be faffed to work out the calories in everything he eats