Exactly... without adequate fuel intake you will be fighting and uphill battle in thigh deep snow against the effects of cold exposure. Obviously having appropriate clothing is important for keeping the heat in, but a 10 inch thick parka isn't going to make you warm if you aren't generating heat from the inside. And food is necessary to generate heat.

You're really up against the odds in the cold. There's always lots of emphasis on having the right equipment, but equipment isn't going to do you a hill of beans if you're energy deprived. Lots of people die of exposure with backpacks full of 'appropriate' gear strapped to their backs, and lots of knowledge and experience behind them, because they were calorie deprived before they got into the situation they thought they were trying to get away from. Hikers caught in sudden snowstorms, for example, likely aren't calorically prepared to survive unexpected cold and poor conditions.

I know we've had the discussion about how difficult it is to eat 5,000 calories or more a day, But I've gained a new appreciation for the reason why it is so important that all attempts be made to eat as much as possible. Even if you consider yourself "overweight" or at least "overfat", you still need to take in the type of calories that your body can use rapidly. Don't expect your body to suddenly decide to use your fat stores for energy, the exposure will get you before your body makes that adaptation.

MNS