(Fat on the hips, thighs, and buttocks has a higher concentration of omega-3 fatty acids and is meant to be used for lactation.) The body begins to burn old adipose tissue in the waist, shoulders, and back, making those areas smaller. Subcutaneous fat increases in the cheeks and lips, making the face appear rounder, with slightly less emphasis on the jaw as the lower portion of the cheeks fills in.  Male-to-female hormone therapy causes the hips to rotate slightly forward because of changes in the tendons. Hip discomfort is common. This can cause a reduction in total body height. If estrogen therapy is begun prior to pelvis ossification, which occurs around the age of 25, the pelvic outlet and inlet open slightly. The femora also widen, because they are connected to the pelvis. The pelvis retains some masculine characteristics, but the end result of HRT is wider hips than a cisgender man and closer to those of a cisgender woman. HRT does not reverse bone changes that have already been established by puberty. Consequently, it does not affect height; the length of the arms, legs, hands, and feet; or the width of the shoulders and rib cage. However, details of bone shape change throughout life, with bones becoming heavier and more deeply sculptured under the influence of androgens, and HRT does prevent such changes from progressing further. The width of the hips is not affected in individuals for whom epiphyseal closure (fusion and closure of the ends of bones, which prevents any further lengthening) has taken place. This occurs in most people between 18 and 25 years of age. Already-established changes to the shape of the hips cannot be reversed by HRT whether epiphyseal closure has taken place or not. Established changes to the bone structure of the face are also unaffected by HRT. A significant majority of craniofacial changes occur during adolescence. Post-adolescent growth is considerably slower and minimal by comparison. Also unaffected is the prominence of the thyroid cartilage (Adam's apple). These changes may be reversed by surgery (facial feminization surgery and tracheal shave, respectively). During puberty, the voice deepens in pitch and becomes more resonant. These changes are permanent and are not affected by HRT. Voice therapy and/or surgery may be used instead to achieve a more female-sounding voice. Facial hair develops during puberty and is only slightly affected by HRT.