*thinks back to age 13*
Nothing for breakfast proper but a sausage roll from the canteen at 10.30am (morning break), usually. Past the age of 11 or so I've always found eating a meal in the morning challenging. I tend not to be hungry until 9 or 10am so I eat breakfast at my desk now. At 13 it was in the classroom before school.
Phew. I was getting worried that I was the only one! Similarly, I stopped liking breakfast at the age of 12-13 - the compromise I came to with my parents was that I would have a very small yogurt or chocolate mousse (mostly air), and they wouldn't nag me.
+2
I think it was around that age I gave up on the compromise (since I was maybe 9 or 10?) yoghurt and did just fine on nothing until at least lunchtime, except perhaps a chocolate bar if I was doing something that required concentration. I don't get hungry until I start eating, though I'll start to feel a bit nauseous (though still not hungry) in the late afternoon if I don't.
I'm also suspicious that this is related to my tendancy towards being nocturnal: I can override my body by being awake in the morning, but my metabolism takes a while to catch up. Note that delayed sleep phase is natural and common in adolescents, and as a species they tend to be more functional if you go along with it...
These days I force myself to eat more regularly, because the build-up of excess bile causes horrible TMI bowel nastiness later if I don't. If I know I'm going to need energy (eg. for cycling), I'll bootstrap my hunger reflex with something easy like chocolate before making myself eat proper food.
Like most things food-related, I'm acutely aware that this makes me a) unhealthy and b) a freak - accepting this and learning not to care what other people think is however a work in progress.