Adequate thyroid function helps one to stay warm in cold environments. Scientific research has shown that certain foods have anti-thyroid effects. These include soy, as well as the cruciferous veggies: broccoli, Brussels sprouts, cabbage, and cauliflower. It may be wise to avoid these when you're camping in the snow.
My experience, based upon a sample size of one, is that certain other things have slight warming effects. These include azuki beans, black-eye peas, beef, lamb, kasha, and ordinary black tea.
Kasha is roasted buckwheat groats. Cook 1/2 cup of kasha in one cup water. It doesn't take much time.