Bulldog,
My first trip up I took everything including the kitchen sink. Neeedless to say, beside the alien trying to crawl out of my right eye, I had zero appetite from 12,000' back to 10,000'.
Also, the food I took, I liked but I would not take them hiking with me for years. I was so turned off by them after this trip.
Over the years, I have found I can eat over 12,000' when I do not push hard...those days are rare. There are many nights I have not had diner above 10,000' after a hard day. I will usually start snacking late in the evening just before tossing and turning time. My first meal usually in the morning.