Vitamin D is important for your health, but there are signs that you could use a little more in your life. Eat This, Not That! spoke with Dr. Nima Majlesi, ED of Staten Island University Hospital about the three major signs that you are lacking vitamin D. Dr. Majlesi shared that bone pain is a major warning sign that you need the vitamin, saying "Lack of vitamin D will affect calcium deposition in bone and potentially lead to conditions of bone loss or deformity." Other signs to look out for include muscle weakness and depression. One way to up your vitamin D intake? More sunshine! Do you think you get enough vitamin D? Are you experiencing any of these symptoms?