Читать книгу Pathy's Principles and Practice of Geriatric Medicine - Группа авторов - Страница 336

The prevalence of obesity (body mass index [BMI] >30 kg⁻²) increases with age until approximately 60 years of age, remains stable until about 70, and then declines.^2,3 Studies indicate that flux in both weight loss and gain in older adults is associated with adverse health outcomes, such as decreased functional status, institutionalization, and increased mortality. Changes in body composition with ageing are also an important consideration. A decline in lean body mass occurs in the third decade of life. This loss in lean body mass, much of which may be due to a more sedentary lifestyle, is offset by gains in fat mass that continue until age 65–70. Older people have a higher proportion of fat to lean body mass than younger adults of similar body weight. It has been estimated that fat‐free mass diminishes by as much as 70% between the ages of 30 and 70. Studies in exceptionally healthy elders indicate that very small weight decreases (e.g. 0.1–0.2 kg per year) are normal with ageing; therefore, weight loss should never be dismissed as part of the ageing process but rather as a shift in the proportion of fat to lean muscle mass.²

Most studies of BMI in ageing have been conducted in the United States (e.g. the Baltimore Longevity Study, the New Mexico Study, and the older age group of NHANES III [National Health and Nutrition Examination Survey]) and in Europe (e.g. SENECA [Survey in Europe on Nutrition and the Elderly – a Concerted Action] and the elderly part of EPIC [European Prospective Investigation into Cancer and Nutrition]). One study including diverse geographic and ethno‐racial groups was the International Union of Nutrition Societies (IUNS) cross‐cultural study ‘Food Habits in Later Life’. This study of elders 70 and older from communities in Australia, Greece, China, Japan, the Philippines, and Sweden showed that on average, BMI for Caucasian men and women is about 25 kg⁻², with the highest for Greek women (30 kg⁻²). Filipino and Chinese had average BMIs between 20 and 22 kg⁻². The estimated fat‐mass gender differences were apparent with women averaging 43–50% and men 25–35%, but differences in fat mass between ethno‐racial groups were less striking.