Well, I had to (eventually) just let go of my 13yo actually eating something that I considered a reasonable breakfast at about this age.
It just doesn't work for her (and she has many of the same problems with nausea if she eats 'wrong' or not at all).
Fruit smoothies work for her. I use frozen fruit and half-and-half for calories. I can also add powdered mineral supplements to it if I'm truly concerned, say, about her calcium intake.
I also make "breakfast cookies" that are basically "Monster" cookies made with sunbutter, orange juice concentrate (fortified with calcium) or pumpkin, flax seeds, oats and other grains, and craisins or raisins. Sometimes she likes those, and being home-made, they don't have the added sweeteners that make things "too sweet" like commercial breakfast bars do.
Sometimes she just grabs a snack about 10:30 once she's had a chance to be awake for a bit longer. Teens often switch their eating habits and sleep needs anyway-- just something to think about there.
I'd also invite HER to come up with some alternatives-- I've found that my DD is much more willing to try HER ideas than mine.