Explain Basal Metabolism Rate (BMR) - Ageing?

From age 25 years, the basal metabolism decreases by about 2 percent for each decade due to the increasing proportion of body fat and lesser muscle tension. Average decreases of 2.9 and 2.0 percent per decade, respectively, for men and women of nonnal weight (BMI of 18.5 to 25.0 kg/m2 ) have been calculated more recently (Food and Nutrition Board Institute of Medicine, USA, 2002). You may recall reading about these changes associated with ageing earlier in Unit 2 as well. The decline in basal metabolism is less in persons who remain healthy and pursue vigorous activity in their later years. The ability to maintain normal body temperature is also lessened and hypotheimia in the elderly can be especially dangerous.