He's almost 16 & has always struggled to eat breakfast - just no appetite first thing in the morning. He also hates most "breakfast foods", preferring left-overs or a mug of soup or a slice of fruit pie, but not till about half eleven, which is what happens at the weekends. I watched him nibbling his way through one small plain biscuit the other morning, clearly forcing it down because "breakfast is good for you" & told him he could stop bothering if he wanted. He does have at least half a pint of milk at "breakfast time" so some calories there. He won't take anything to eat on the bus or at break - not hungry till lunchtime.
I was just the same, hating soggy cereal, preferring leftovers & at the same age my mum stopped nagging me about it. I still don't eat breakfast unless it's a full English in a hotel at about half ten