Hypothyroidism
The function of the thyroid gland is to regulate the metabolism of the body. When hormones released by the gland are adequate, the body maintains its optimal metabolic processes. When there is hypothyroidism, that is, the thyroid hormones produced are lower than the body's requirements, the metabolism slows down. This results in poor production of heat and the person feels chilly even at normal room temperature. If it is hypothyroidism, the following symptoms might accompany the chilliness - hair thinning, weight gain, lethargy, and fatigue.