I grew up as a fat kid so there really is no way to sweeten this, high fructose corn syrup is your enemy. Plain and simple.
Since kids can vary as much as a spectrum of light, just get them to either exercise, or throw a banana split atop a treadmill and fasten your child to it, just make sure it functions like a baby seat. Your kid will be like Fred Flinstone in no time. =D
That reminds me, vitamins are cool. Anyway just research weight loss enough and you'll get it eventually.