R.B.
I don't think that with or with out the toy my kids would eat any more or less than what they do.
When we go to a fast food MAYBE once a month its a treat for them. I seen someone put they can have the toy with apples and juice... well we have that at home. We don't have fries and they don't get sprite at home.. all goes along with getting the treat. I don't think they are distracted by the toy to eat like they should. We have a 40-45 min drive home... by the time they get home they have eaten what they are going to eat while playing with their toy. If they are still hungry by the time we get home, they come in and finish thier food.. or we throw it away if they are done.
As far as my older kids.. they all stopped asking for a happy meal around 7/8. When they realized that they don't like the toy or they have different sandwiches that they like better on the menu.