Food on the mountain is adequate but not terribly exciting. All the menus in the teahouses are the same - eggs, potatoes, rice, pasta, pizza, yak steaks, milk tea, hot tang, bottled water, some herbal teas, pop, popcorn, chocolate bars, white bread. Lots of yak cheese which they put on everything. There are some fresh vegetables near the base of the mountain but higher up vegetables are canned. Everything is cooked over a wood/yak dung cookstove. I had good yak steak and yak steak that was worse than shoe leather. One day, as a treat we got little cocktail hot dogs and spam. When camping we had the above plus chicken, hot chocolate, jam, cookies and canned fruit. Everything has to be carried up on someone's back, there are no refrigerators and cows are sacred to the Hindus. There were lots of no meat days. Considering what they have available to them they do a good job.
They tell you to bring your own snacks and freeze dried food. I took over a bag weighing over 20 kilos just with snack food in it for the family. Snack food included nuts, granola bars, power bars, chocolate bars, canned tuna and chicken, sesame seed bars, mints, dried fruit, fruit jube jubes, beef jerky and power gel.
Altitude suppresses you appetite, you often feel sick to your stomach and you get tired of the same food all the time so you have to force yourself to eat. You are using up a lot of energy hiking and at higher altitudes breathing and surviving. Most people take a diuretic to help them acclimatize. It is natural to lose weight but it is not a weight loss program I would recommend.
After being on the mountain for awhile you really crave things like fresh fruit and vegetables, a hamburger, steak. There is a lot more variety in Kathmandu but again you never eat anything in a third world country unless it is well cooked, you bought and washed it yourself with safe water, or it is a high class restaurant you trust.
When everyone arrives home I can't imagine my grocery bill.