Why are some people always cold?

Human beings generate heat while doing muscular movements such as exercise, metabolism etc., Most of the heat is used to maintain our body temperature and make us warm. However, some people are always cold, this may be due to hyperthyroidism. 

                                                In hyperthyroidism, our thyroid gland which regulates metabolism does not function properly. As a result, our metabolism slow down and less heat is generated. 

Another reason for coldness is may be due to a disorder called Raynaud's disease. When a person is having this disorder is stressed or exposed to cold, his arteries in his hands and legs become narrow. Hence, warm blood is not transported efficiently throughout his body. And also Iron deficiency and smoking are said to be some of the reasons.