DS1 is short for his age (6) and we are seeing a pediatrician for this. He is also getting quite fat. My mum has him 3 days a week for me (sometimes more) while I work. DP works away all week so it's a great help for me. I have spoken to her before about not letting him have too many treats, he is a fussy eater but will quite happily eat cheese on everything, pizza, chocolate etc. I feel like I need to put my foot down as I know he is getting crap while I'm not there. I have tried upping his exercise (buying a trampoline, swimming lessons, playing out with footballs etc) but it doesn't seem to be having much effect 
It would break my heart if he was bullied/hated the way he looks when he is older and im scared if he is like this at 6 what will he be like at 10/11 when he starts thinking about body image. I don't believe that any 6yr old should be on a diet but I really need to take control of this. Any suggestions appreciated!