We struggle with this as well with DS who is a picky eater esp in the morning and not attuned to hunger signals until it's past the point of no return. Will he eat yogurt? Chobani has a relatively new 'reduced sugar' line now that I get at costco and has a lot less sugar than most flavored yogurts. For DS we've had success with protein shakes. We get the Atkins premade ones as those are the ones he and i have found most palatable. If I feel like he's not eaten enough in the morning I'll just send him to school with one of those.