DS1 is SO skinny. He put on a pair of pants the other day size 18-24 months and they fit him - he'll be 5 next month. You can clearly see all his vertebrae and his ribs, his arms are thinner than BabyG's arms (he's 13 weeks old!) and his face just looks gaunt.
However - he eats like a horse, almost adult sized portions and snacks in between. I have had him checked over and he's healthy but I do fret about his skinniness.
I know I'm not alone