I've been overweight, and I know how horrible kids (and adults, for that matter) can be when you're sporting anything above size 6. For that reason, I'd hope they wouldn't end up overweight - just because I know society as a whole is extremely fat shaming (yes, I do it too) and I wouldn't want them to feel bad.
However, if they ended up overweight for whatever reason (weight gain isn't solely caused by "eating too much" - there's a lof of diseases and unfortunate circumstances that can make you gain weight), I would never ever shame them. I would never do portion controls. I would never tell them to go outside and play. I would never make them feel bad about their size, because that's how you ruin your child's confidence and body image.
I wouldnt go as far saying "child, dont be fat", but I would heavily promote sports and basically make sure the kid is healthy. I think if u do that, and make sure to be an example, the kid will mostly likely follow ur footsteps.