Changes in body fat and muscle in manual workers at and after retirement.

The changes in body fat and muscle in 73 men retiring from manual work have been measured in a longitudinal anthropometric study. Body fat increased by about 3% and body muscle decreased by about 1% between measurements made just before retirement and again 1 year later. The decline in muscle was even greater in a subgroup of 22 men who reported that their activity was less after retirement: but a subgroup of 11 whose activity was said to have been greater after retirement showed an increase in body muscle. A sub-sample of 26 men were measured on five further annual occasions (Fig. 1). The initial increase in body fat was reversed, and fat measurements fell back significantly to or below the pre-retirement values. Body muscle, however, continued to decline steadily at the initial rate, and the ratio of thigh muscle area to body mass fell significantly in retirement in the group as a whole. The possible contributions of ageing and of changes in energy balance and physical activity to these findings are discussed.