I have to put the title in quotes here, as it is terminology I neither use nor accept, but I was invited to be on a live panel for an interview on Huffington Post Live today: "How To Talk To Children About Obesity."
My answer to that question is "Don't."
Model and live a healthy and positive life with your kids. Eat wholesome family meals most of the time. Be active together. Prioritize sleep. Nurture healthy body image based on enjoying one's body and what it does, not its appearance or size. Do not comment on or put value on anyone's body size or shape.
There is no need to talk about size, large or small. It doesn't do anything good, and it can do a lot of harm. Weight stigma is poison: harming those of all sizes just as racism is toxic to the victim and the perpetrator.
And here is a few more "don'ts."
Don't look at the weight of children and think you know anything about their health, their eating habits, their parents, their self-control, or their lifestyle. You do not.
Don't, moms and dads, think that your doctor has training in this area: they probably do not.
If you suspect an eating disorder go to a specialist. Go to a specialist with recent and ongoing training and active membership in eating disorder specific organizations. Just because someone calls themselves an eating disorder expert doesn't make it so.
Don't, parents, if your child is average weight, believe that this means you deserve a gold star for parenting. Your child's weight is largely a function of genetics. Love them, feed them well and calmly, do things together, make sure they have safe and loved lives. Let weight take care of itself. There is nothing recommended for "obesity" that should not be happening for all children.
Don't comment online with your head in your behind: it is not a good look for you.