predictor of increased mortality in older community‐dwelling male veterans. Over a two‐year follow‐up period, mortality rates were substantially higher in the 13% of the population with involuntary weight loss (28%) than in those who did not lose weight (11%), even after adjusting for baseline age, body mass index (BMI, the weight in kilograms divided by the height in metres squared), tobacco use, and other health status and laboratory measures.3
Weight loss is strongly associated with a 76% increase in mortality risk among home‐bound older adults, along with male gender and age. This effect of weight loss persists after adjusting for initial BMI, smoking, health status, and functional status.4
In nursing home residents, a 10% loss of body weight over a six‐month interval strongly predicted mortality in the ensuing six months.5 When compared with controls, the 16% of subjects who lost at least 5% of their body weight were 4.6 times more likely to die within one year.6 In another study of long‐term care residents, a 10‐fold increased risk for death was seen for people who lost 5% of their body weight in any month compared with those who gained weight.7
Weight loss is also associated with a decline in functional status. Weight loss of more than 5% in community‐dwelling women age 60–74 was associated with a twofold increase in risk of disability over time, compared with women who did not lose weight, after adjustments for age, smoking, education, study duration, and health conditions.8 The Health Aging and Body Composition (ABC) study provided longitudinal data of weight, BMI, body composition, and function in a cohort of older people (70–79) who were functionally independent at baseline.9 Weight loss during the first four‐year period was associated with loss of lean and fat body mass; but during weight gain episodes less gain in lean body mass than loss during weight loss was observed, particularly in obese men.10 In the Health ABC study, nine‐year BMI trajectories showed general trends in BMI decline in women and men. However, men who were obese at baseline had a more significant decline in gait speed and strength than others, with no association with loss of lean body mass. Obese women had more significant lean body mass loss than others, but there was no association between BMI trajectories with function or physical performance according to time.11 Weight loss and undernutrition are also related to functional decline in nursing home residents.12
Body weight and weight adjusted for height (BMI) are easily obtained clinical measurements that can predict adverse outcomes in older people.
Weight loss and frailty
Frailty syndrome is a multifactorial impairment in health status predictive of adverse living events, such as loss of independence, falls, hospitalization, adverse drug events, decompensation of chronic diseases, admission to nursing settings, or death.1,13 According to Fried’s model, unintentional weight loss of ≥10 pounds (about 4.5 kg) or ≥5% of body weight in the prior year is one of the five criteria of the frailty phenotype.
The English Longitudinal Study of Aging (ELSA) showed that in subjects older than 65, contribution of weight loss to the frailty phenotype was the lowest among all criteria.14 Weight loss was also the least prevalent frailty criterion (23.8%) among centenarians, with at least 95% of them having one frailty criterion.15 Only 20% of the oldest‐old frail subjects (mean age 88) presented with unintentional weight loss compared to a much higher proportion of subjects with low gait speed (97%), low muscle strength (84%), low physical activity (92%), or exhaustion (66%).16 This later study evidenced two different frailty profiles (two dimensions) with multicomponent analysis. Weight loss and exhaustion were linked in the first dimension and the three other criteria in the second dimension. Note that the first dimension is similar to ‘impaired general condition’ syndrome. Indeed, in frail subjects, anorexia was associated with weight loss, exhaustion, and low gait speed but not decreased physical activity or muscle strength.17
Two different prefrailty profiles were suggested in the TILDA study including subjects older than 50: the first (PF1) associated weight loss and/or exhaustion, and the second (PF2) associated one or two of the physical criteria (low gait speed, decreased physical activity, or muscle strength).18 PF1 participants were more likely to be women, younger, with lower BMI, functionally independent, and with fewer comorbid conditions (diabetes, hypertension, arthritis) but a higher incidence of osteoporosis. After a 10‐year follow‐up, mortality rate and disability progression were much lower in the PF1 group than PF2, even after adjusting for confounders.
However, these prefrailty profiles may have different trajectories in older people, particularly those older than 85. Weight loss–associated frailty or prefrailty syndrome may also benefit from different preventive management than others. This field in frailty management deserves specific studies.
The WHO Guidelines on Integrated Care for Older People (ICOPE)19 propose screening and management strategies for older subjects at risk for unhealthy ageing. Weight loss and anorexia are grouped into the malnutrition item, calling for integrative management of nutritional risk. The impact of this program is not known at this time.
Weight loss and sarcopenia
Sarcopenia was operationally defined as an appendicular skeletal muscle mass divided by height in metres of more than two standard deviations below the young normal mean. Using this definition, Baumgartner et al. found that 14, 20, 27, and 53% of men age less than 70, 70−74, 75−80, and over 80, respectively, met this definition. In women, 25, 33, 36, and 43% in the same age groups had sarcopenia.20 Weight loss may indicate an underlying decrease in muscle mass, but sarcopenia may occur without a global change in weight.21 Weight loss and regain cycles are common in older people and result in global weight loss as compared to weight stability.22 Men with a weight loss‐regain cycle showed lower lean mass compared with their stable counterparts, whereas women with a weight loss‐regain cycle showed lower fat mass compared with women in the stable group.22 At a BMI cut‐off of ~27 kg/m2, 14% of men less than 70 years old and 29% of men over 80 were sarcopenic and obese, and 5% of women less than 70 years old and 8% of women over 80 were sarcopenic and obese. The last consensus paper proposed for sarcopenia management is based on screening for lower muscle performance and not weight loss.23 Indeed, measuring muscle mass in routine practice is difficult; low‐calf circumference was proposed as a surrogate for global low muscle mass estimation. Finally, in subjects followed for cancer treatment, an abdominal computed tomography L3 slice allows the estimation of muscle index.24
The relationship of weight loss to mortality
BMI of less than 22 kg/m2 has been associated with a higher one‐year mortality rate and poorer functional status among older community‐dwelling people.25 The risk for higher mortality in men older than 65 begins at a BMI of less than 22 kg/m2 and increases to a 20% higher risk in men older than 75 with a BMI of less than 20.5 kg/m2. Similarly, a higher mortality risk in women begins at a BMI of less than 22 kg/m2 in women older than 65 and increases to a 40% higher risk in women older than 75 with a BMI of less than 18.5 kg/m2.26 BMI less than the 15th percentile is an independent predictor of 180‐day mortality following hospitalization.27
Although there is a strong association between BMI and mortality, the key factor in mortality risk appears to be recent weight loss. After excluding subjects with weight loss of 10% or more of their body weight, there is little relationship between BMI and mortality. In people over 50 who reported an unintended loss of 10 lb (~3.7 kg) or more in the year before evaluation, the age‐adjusted death rate was much higher compared with people who voluntarily lost weight through diet or exercise or who maintained or gained weight.28 Nearly all of the observational studies on body weight have found that any weight loss is associated with increased, rather than decreased, risk for death.
The data suggest that obesity in older adults may not be an important clinical target for reducing mortality and that a preferred public health emphasis for this age group would be to increase