The menopause is associated with changes in body composition: a decline in bone mineral content, a decrease in collagen synthesis, a loss of lean body mass and an increase in total and abdominal fat mass. Oestrogen deficiency seems to play a role in the menopause-related changes in body composition, but life styles (diet, exercise, smoking habits, alcohol consumption) are also involved. The time course of the decrease in lean mass deserves attention since it could justify specific actions, i.e. exercising or hormonal treatment, early during the perimenopausal period. A decrease in fat-free mass may be responsible for a decrease in energy expenditure favouring weight gain if the calorie intake is not reduced.