Dieting in children is a poor idea; in babies it's worse.

One thing which can be looked at, however, is increasing the baby's
activity (I didn't see the original post, so forgive if this has already
been addressed).  A baby can expend a lot of energy in play if encouraged
and assisted to do so.  Water play is especially good.  But I wouldn't
worry overly much about the obesity.  Is the iron status good?

Arly in Northern Utah's mountains <[log in to unmask]> MS Nutrition, CLE, IBCLC
If you have built castles in the air, your work need not be lost; that is
where they should be.  Now put foundations under them. -Thoreau