European Journal of Clinical Nutrition (2000) 54, Suppl 3, S33±S39 ß 2000 Macmillan Publishers Ltd All rights reserved 0954±3007/00 $15.00 www.nature.com/ejcn Body weight and weight change and their health implications for the elderly JC Seidell1,2* and TLS Visscher1,3 1Department of Chronic Diseases Epidemiology, National Institute of Public Health, Bilthoven, The Netherlands; 2Institute for Research in Extramural Medicine, Free University Amsterdam, The Netherlands; and 3Netherlands Institute for Health Sciences, Erasmus University, Rotterdam, The Netherlands After the age of 60 y, body weight on average tends to decrease. The contribution of fat mass to this weight loss is relatively small, but fat tends to be redistributed with advancing age toward more abdominal (particularly visceral) fat. Anthropometric data are relatively poor indicators of these aging processes. This may be one of the explanations why the relationship between high body mass index and mortality is less pronounced in older than in younger people. Reduced lipolysis in the visceral fat depot with aging is among potential explanations why increased visceral fat seems to be less harmful in elderly subjects compared to young adults. Even though the relative contribution of increased fat mass to mortality may be less pronounced in elderly people, the impact on disability and functional limitations is found to be important from both a clinical and a public health point of view. At the other end of the scale studies have shown that low body mass index and weight loss in the elderly are both strong predictors of subsequent mortality. This cannot be explained by effects of smoking and early mortality after baseline. There are only few systematic studies comparing the predictive validity of different anthropometric data for mortality. One recent prospective study showed that a high waist circumference (in non- smoking men) may be a better predictor of all-cause mortality than high body mass index and waist=hip ratio. Low BMI was a better predictor of mortality than low waist circumference. In conclusion changes in body composition and fat distribution with aging are poorly captured by standard anthropometric data. Low lean body mass is probably better re¯ected by low BMI, whereas increased (abdominal) fatness is better re¯ected by increased waist circumference. Descriptors: aging; obesity; fatness; mortality; morbidity; fat distribution European Journal of Clinical Nutrition (2000) 54, Suppl 3, S33±S39 Epidemiology of weight status and aging Effect of age on body composition and body fat distribution In cross-sectional studies the prevalence of high body weight or obesity (body mass index (BMI) > 30 kg=m2) One fundamental problem in the interpretation of such increases with age up to about age 60 and then declines (see epidemiological data is that anthropometric data have Figure 1). different implications for body composition at different There can be several explanations for this: ages. For instance from densitometry (Deurenberg et al, 1991) it has been calculated that selective survival (obese young and middle-aged per- sons have died prematurely); percentage body fat cohort-effect (old people come from cohorts in which 1:20 Â BMI 0:23 Â Age 10:8 obesity was less common); 2 people start to loose weight after age 60 y (Shock, ÂSex men 1; women 05:4 r 0:79 1972). This implies for instance that at a BMI of 30 kg=m2 a man All three possibilities are likely to play some role, but aged 20 y has 24.4% body fat, whereas a man of 80 y has their exact quantitative contribution has not been studied 38.8% body fat and that women have a much larger relative systematically yet. There are some changes associated with fat mass than men at every age and level of BMI. In aging which could actually be expected to have an effect in addition, body fat is redistributed with increasing age in the opposite direction, such as a decline in stature which, the sense that more of it becomes located in the abdominal even when weight is maintained in all people, would lead to cavity (visceral fat) (Borkan et al, 1985; Seidell et al, 1988; an increase in the prevalence of obesity with aging (van Figure 2). The reason for this redistribution is not really Leer et al, 1992; Launer et al, 1995). known, but declining testosterone and growth hormone levels in combination with declining rates of lipolysis of visceral fat with aging (Ostman et al, 1969) may play a role in men. Low testosterone levels have been shown to be *Correspondence: JC Seidell, Department of Chronic Diseases Epidemiology, National Institute of Public Health and the Environment, associated with increased visceral fat mass in men (Seidell PO Box 1, 3720 BA Bilthoven, The Netherlands. et al, 1990). In women the declining oestrogen levels after E-mail: [email protected] menopause may be a critical factor. Body weight and weight change JC Seidell and TLS Visscher S34 Figure 1 Prevalence of obesity by age in men and women in the United Kingdom 1997 (Health Survey for England 1997). Figure 2 Visceral fat area as a percentage of total fat area in the abdomen assessed by computed tomography by age in men and women (adapted from Seidell et al, 1988). In addition, weight loss at older age does not re¯ect the nounced with aging (Andres et al, 1985; Stevens et al, same changes as at younger age. In the elderly, it is much 1998, Waaler, 1988; see Figure 3). more closely associated with loss of lean body mass than in There are several potential explanations for this: young adults. This accelerated loss of fat-free mass in older people is often called sarcopenia (Poehlman et al, 1995). 1. BMI is not an optimal indicator of body composition in Involuntary weight loss is frequently reported in elderly the elderly (Visser et al, 1994). Allison et al (1997) patients and usually caused by acute or chronic diseases speculated that the U-shaped relation between BMI and (Fischer & Johnson, 1990). mortality resulted from an inverse linear association In conclusion, although the prevalence of obesity between lean body mass and mortality and a positive declines with age after age 60, this does not imply that association between body fat mass and mortality. The excess fat storage is uncommon in the elderly; progres- BMI does not allow separation of these two phenomena sively more fat is stored in the abdominal cavity. Anthro- (Allison et al, 1997). pometric data such as weight, height and skinfold 2. Selective survival: obese persons at high risk have died thicknesses seem inadequate to measure these changes. prematurely and what remains is a selection of relatively healthy obese subjects. 3. Ceiling effect: absolute mortality rates increase with age and for instance at 90 y of age 15 y mortality will be Effect of age on the association between BMI and health close to 100% regardless of any risk factor status. 4. Cohort effect: obese subjects now at an old age have Mortality been exposed to lifestyles and environments that are Many studies have documented that the U-shaped relation different from those of future obese elderly persons. between BMI and all-cause mortality becomes less pro- For instance someone now aged 85 y was born at a time European Journal of Clinical Nutrition Body weight and weight change JC Seidell and TLS Visscher S35 Figure 3 Ten-year mortality in Norwegian men by age and BMI (adapted from Waaler, 1988). Lower line: age 45 ± 49; middle line: age 60 ± 64; upper line: age 75 ± 79. when life expectancy at birth was about 50 y and the instance, obesity has very little effect on total mortality at most frequent cause of death was infectious disease body mass indices below 40 kg=m2 (Pettitt et al, 1982). whereas obesity and co-morbidities such as heart disease were relatively uncommon. Visscher et al attempted to Morbidity separate age and cohort effects in aging men and Much of the available data on BMI and health are restricted showed that when a cohort effect is excluded age has to mortality. There is, however, increasing evidence that an little effect on the relative risks associated with high excessive BMI in elderly women and men is associated BMI (Visscher et al, 1999). with impairment of health, disability and reduced quality of 5. Excess fat is less detrimental in older than in younger life in terms of functional limitations (Launer et al, 1994; people. This issue will be explored further in the section Visser et al 1998a, 1998b). In several studies Visser et al on body fat distribution. (1998a, 1998b) explored the possibility that disability is Although the relative risks of a high BMI may become caused by low lean body mass and high fat mass. In all less pronounced with aging, the relatively high prevalence instances they concluded that particularly high body fat of obesity in the younger elderly, in combination with high mass is associated with mobility disability and general mortality rates (absolute risks), make a high BMI an disability even in the very old (Figures 4 ± 6). important public health issue. Comparative data on these risks in young and elderly are At the other end of the scale studies have shown that low not available, but given the large incidence of functional BMI and weight loss in the elderly are both strong pre- limitations and disability in the elderly this is certainly dictors of subsequent mortality. This cannot be explained becoming a more important public health issue with advan- by effects of smoking and early mortality after baseline cing age. (Visscher et al, 1999). There has been some debate as to whether or not the Effect of age on the association between weight change ¯attening of the BMI:mortality curve with aging and the and health upward shift of the nadir (the point of minimum mortality) of the curve with age should lead to the conclusion that cut- On average people above about 60 y of age lose weight off points for obesity should be higher in older than in when aging.