Whole grains contain complex carbohydrates, which require more energy to break down. Your body uses this energy as fuel to give you warmth on those cold winter days. Whole grains are a rich source of a number of vitamins, especially vitamin B and they help your thyroid gland to function optimally. Thyroid gland helps to regulate your body temperature and keeps you toasty warm in winter. So, these winters add a lot of brown rice, oats, barley and millets like jowar and bajra to your diet.