Now fair enough, if you're on expedition for a week or more in isolated mountain conditions in Outer Narnia or somewhere! But for a two-day climb in good summer alpine conditions with one or two overnight bivvies it's all a little bit "Bear Grylls overkill".
If you don't eat anything for two days on the hill you will certainly feel like crap, get really tired, make silly potentially dangerous mistakes, and not make your summits. But you will not die of starvation, scurvey, clap, scrofula, galloping anaemia, terminal constipation or any other of the horrors that nutrition fanatics try to scare you with.
Like many other aspects of mountaineering (extreme soloing aside), mealtimes have been hijacked by people who want to sell you stuff or show you just how bloody clever they are. And for people who are just starting out, or those trying to extend their enjoyment of bivvying in mountains this can be pretty worrying and confusing stuff.
Nutrition is indeed a complex subject that requires a sound knowledge of food, drink and body chemistry, and therre is nothing wrong with studying this subject and giving yourself a healthy balanced diet in readiness for the summer bergs. Nutritionally preparing the body, however,is done months before your trip in tandem with your alpine physical fitness programme.
Because once you are on the hill, all you will be doing is pumping fluids, carbs and proteins into your head to help maintain the energy levels you built up whilst in training.
The trick is to work out a "personal system" of cooking and feeding "specific to your needs" on the mountain, that is easy and, more importantly, enjoyable enough to maintain your "energy high" so you can enjoy your bivvies, acheive your summits, and get down in one piece.
MY WAY OF DOING IT!
I am a lazy guy, in fact, on a scale of one to ten I must rate a 9.5 on the "Idle Meter", so I like to keep things really simple.
All my hot drinks and foods are made on a Jet Boil Stove, with the simple caveat that no foods or beverages ever touch its insides. It is only for heating water or small "boil-in-the-bag" foods. That way, I never have to sod about cleaning it!
From long experience on army active-service and civvy expeditions I know that most dehydrated ration packs contain everything I need nutritionally for a week of mountain yomping.