I am certainly not a nutritionist, but your body burns a lot of calories trying to stay warm when you are out in the extreme cold of the polar regions. Making sure you eat high caloric density foods (e.g., high protein and fat foods) before you go out onto the sea ice or on a long snowmobile drive to your sampling site, for example, will help keep your core warm. Dehydration is also something to watch out for. People generally don't drink enough water when it's cold because you don't experience thirst the same way as when it is hot and humid around you, and people don't want to drink cold water when it's well below freezing outside! So a thermos of water, tea or soup is your best friend to stay hydrated and warm while in the field.