- Top of page
- Effect of Age on Body Weight, BMI, and Body Composition
- Effect of Age on the Relationship between BMI and Mortality (Cross-Sectional Studies)
- Effect of Changes in Weight on Mortality (Longitudinal Studies)
- Effect of BMI on Morbidity
- Energy Intake and Expenditure
In developed countries, there is a general increase in body weight and body mass index (BMI) with age, until ∼60 years of age, when body weight and BMI begin to decline. The proportion of intra-abdominal fat, which is related to increased morbidity and mortality, progressively increases with age. There is also a progressive decline in energy intake and daily total energy expenditure (165 kcal/decade in men and 103 kcal/decade in women in developed countries), which is primarily due to a decrease in physical activity, and to a lesser extent, a decrease in basal metabolic rate. The decrease in physical activity is more pronounced in those with chronic disabilities and diseases. The BMI–mortality curves have been reported to move upward (greater overall mortality), become flatter (less effect of BMI on mortality), and in some cases shift to the right (minimum mortality occurs at a higher BMI), for a variety of possible reasons. Weight loss in the elderly has been reported to increase, decrease, or not alter mortality, but the studies are confounded by numerous methodological problems. It has been argued that there may be little benefit in encouraging weight loss in extreme old age (short life expectancy), especially when there are no obesity-related complications or biochemical risk factors and when strong resistance and distress arise from changes in lifelong habits of eating and exercise. In contrast, weight loss in the elderly can reduce morbidity from arthritis, diabetes and other conditions, reduce cardiovascular risk factors, and improve well-being. BMI also predicts morbidity in those without disease. Furthermore, increased physical activity in the elderly, which is an important component of weight management, can produce beneficial effects on muscle strength, endurance, and well-being.