Over the years I have seen and used many different types of food while in the hills in winter. Some worked well and some food like sandwiches I have just carried around and wasn’t able to eat because of the weather. Here is a list of a few things that always work even if the weather is not working in your favour.
I would always have a thermos flask with a hot drink. What you take with you is really a personal choice. If possible coffee should be avoided, because it can dehydrate, when you really need fluids. Consider builder’s tea, fruit or herbal tea and hot Ribena. I also carry a wide neck Nalgene bottle with about 0.5 – 1 litre of water around. Water bottles can freeze but with wide neck Nalgene bottles you can at least hack you way into the bottle again. What should be avoided at any cost are hydration systems with a hose.
Nut mixes are a pretty good idea. So you don’t spread nuts all over the mountains it would be a good idea to but them in a XS dry bag. That way you can snack on the go.
Chocolate bars, Muesli bars and Flapjacks are a great and fast source of energy. However, the likes of Mars bars and Sneakers and some muesli bars can get rock hard in sub zero temperatures. Try bars with little or no caramel and when they are wrapped in plastic take them out and put them in the dry bag with your mixed nuts. I do like to take Tunnock’s Caramel Wafers up the hills. They can get a wee bit hard but the caramel doesn’t get rock solid and the bars are wrapped in paper instead of plastic. You wouldn’t believe how often I see a plastic wrapper flying past me in winter.
A good idea is to have food in the mountains that you can eat without taking your gloves off. Any kind of pie works well (macaroni pie, pork pie, scotch pie etc.). I also take German Stollen cake with me. They have a lot of energy in them and even though you can only buy them up to Christmas they last you all winter. Put your food into a lunchbox for easy access. What definitely doesn’t work well is sandwiches. Sometimes the wind will take the content for a ride. Try to avoid anything elaborate like food you need to prepare in blizzard conditions or meals that requiring cutlery.
The list of food taking up winter mountains is certainly not exhausted. Basically anything you can eat with your gloves on is ideal.