Safe food Ireland have given great tips on how to manage children’s portion sizes
Give them smaller portions of food on their plates to start with, and if they want more food, then give it to them. If they say they’re hungry, offer them something nutritious like fruit and vegetables (for example, an apple or handful of grapes).
Avoid having fatty and sugary snack foods freely available between and after meals.
Don’t pressure them to eat all the food on their plate, allow them to stop when they say ‘I’ve had enough’.
Use plates and cutlery that match their size. Look at the proportions of food you offer during the day, they should be roughly: One third fruit and veg One third starchy foods like bread and potatoes One third dairy (milk, cheese and yogurt) and protein (meat and fish).
See more at: http://www.safefood.eu/Childhood-Obesity/6-Healthy-Habits/Portion-Sizes.aspx#sthash.k3ySQc2g.dpuf