I have been told to "keep an eye on it" about DD's weight several times - now she is over 2 based on BMI but also prior to that - she is just heavy. My opinion is they are overely concerned about weight at too young an age, and not concerned enough about what they are eating. As you know they tend to stop eating so much at 18 months so I think before that is good idea to let them eat as much as they want.

I do wonder sometimes if they can eat because they just like food because I am like that and will eat and eat and eat and level of hunger is irrelevant - but I am lucky in that I don't tend to put on weight - but that doesn't mean am healthy.

Whenever I was given the "keep an eye on it advice" I just tended to have a recheck on what we were doing, decide it was ok and keep doing it.

(DD has a 99 pc head, and heads actually weigh a lot, personally I would do what you are currently doing)