DS1 will be 5 next month and is really thin. Weighs a fair bit less than his 3 yr old brother. Was always on the 75th line for height and weight but over the last year has dropped down to just below the 50th for weight.
Apart from the fact that it is near on impossible to get trousers to fit him and that he has literally no padding on him, his weight doesn't particularly concern me as DH and I were both thin children (not so much anymore!).
What worries me is how much he is affected by the cold. We walk to school in the mornings (about half a mile) and he is literally shaking with cold. His lips and fingers have a blue tinge when he's cold too. I know that he often forgoes playtime at school as its too cold outside for him.
I've just ordered him some thermal underwear but wondered if anyone has any other tips, either diet wise to get him to bulk up a bit or for keeping him a bit warmer.
Should add that he is a dreadfully fussy eater, won't drink milk and has the appetite of a sparrow.