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1 From the University of Pittsburgh, Pittsburgh, PA (JSL and ABN); the Wake Forest University, Winston-Salem, NC (SBK); the National Institute on Aging, Bethesda, MD (TBH); the University of Tennessee, Memphis, TN (FT); and the University of California, San Francisco, San Francisco, CA (SMR)
2 Supported by National Institute of Aging contracts N01-AG-6-2106, N01-AG-6-2101, and N01-AG-6-2103. 3 Reprints not available. Address correspondence to JS Lee, University of Pittsburgh, 130 N Bellefield Avenue, Pittsburgh, PA 15213. E-mail: jung-sun.lee{at}mail.cscc.unc.edu.
ABSTRACT
Background: The frequency and short-term natural history of weight loss in community-dwelling older adults have not been described. Unintentional weight loss may be more likely to continue than intentional weight loss.
Objectives: The present substudy described the frequency of a 5% loss or gain in body weight in community-dwelling older adults at an annual examination of the Health, Aging, and Body Composition (Health ABC) Study and 6 mo later. The weight-management practices used by the participants were also described.
Design: A total of 522 older adults with either a 5% weight gain (n = 116) or a 5% weight loss (n = 171) in the previous year were compared with a random sample of weight-stable older adults (<5% weight loss or gain, n = 235) at the fourth annual visit of the ongoing Health ABC Study. The participants' weight-loss intention and weight-management practices were assessed by an interview. The participants' weight was reassessed 6 mo later.
Results: Compared with the weight-stable participants, the participants who had lost or gained weight at the substudy baseline were more likely to have subsequent weight changes. The direction of the subsequent weight change, however, was more likely toward either maintenance of or recovery from the previous weight change. Only 4% of the participants who gained weight and 11% of those who lost weight continued to gain or lose weight, respectively. Continued weight loss was more common in the participants with unintentional weight loss than in those with intentional weight loss, but the difference was not significant.
Conclusions: Weight changes were common, but most participants, including those who unintentionally lost weight, maintained their weight change or resolved their weight change in 6 mo. Unintentional weight loss appears less likely to resolve than other weight changes.
Key Words: Weight-change intention • short-term weight change • community-dwelling elderly • Health ABC Study
INTRODUCTION
Periods of weight loss or gain precipitated by diseases place older adults at an increased risk of developing progressive weight loss or gain (1–11). This may be because of a diminished physiologic ability in older adults to preserve the homeostatic mechanisms that govern hunger and satiety (2) and thereby help to maintain a steady body weight.
Episodes of weight loss or gain may be more common in older adults than previously thought (11–14). However, few studies have investigated the weight-change patterns in terms of incidence, contributing risk factors, and trajectories of weight loss or gain over time in relatively healthy community-dwelling older adults. Weight loss and gain can be either intentional or unintentional. Unintentional weight loss or gain is often associated with the presence of either severe disease or unrecognized health problems (15–19) and is more likely to continue than intentional weight loss or gain. Intentional weight loss is thought to differ from unintentional weight loss, but whether this is true may depend on the subject's age and underlying health condition. An important step in developing appropriate weight-management strategies to stabilize weight and health in older adults is to elucidate the patterns of weight change in this population.
The objective of the present study was to describe short-term (6 mo) weight-change patterns in elderly participants from previously measured weight changes and from weight-change intentions and to relate these findings to the participants' reported weight-management practices. To do this, we used data from a specially designed substudy of the Health, Aging, and Body Composition (Health ABC) Study. The substudy was designed to understand the frequency, natural history, and contributing risk factors for measured weight changes over 6 mo in community-dwelling older adults aged 70 y who had a clinically significant weight change or not. We were particularly interested in whether the participants who lost weight were more likely to lose weight in the future than were the weight-stable participants and in whether the proportion of the participants who continued to lose weight was greater in the participants who unintentionally lost weight than in the participants who intentionally lost weight.
SUBJECTS AND METHODS
Substudy design and participants
The substudy sample was a subgroup of the Health ABC Study, which is a prospective investigation of functional decline in 3075 biracial community-dwelling older adults aged 70–79 y who were enrolled between 1997 and 1998 (20). The substudy sample was selected at the fourth annual examination of the Health ABC Study between 2000 and 2001 with the use of a nested case-control design (Figure 1). All participants who had a measured weight change of 5%, either a gain (n = 168, or 6.9% of year 4 participants) or a loss (n = 236, or 9.7% of year 4 participants), since the preceding annual examination were included in the substudy. A randomly selected control sample of 248 participants who were weight-stable during the same period was also examined 6 mo later. The participants who participated in the substudy were more likely to be white than were the persons who did not participate in the substudy, but other sociodemographic characteristics and mean body mass index (BMI) did not differ significantly.
FIGURE 1.. Participants of the Health, Aging, and Body Composition (Health ABC) Weight Change Substudy.
The substudy participants were asked to return to the clinic for a 6-mo follow-up visit after their scheduled fourth annual Health ABC Study examination. Five hundred thirty-eight participants (93.6% of the substudy sample) returned or were contacted for the follow-up visit. The proportions of missed visits were higher in the weight-change groups than in the weight-stable group (10% for the weight-change groups and 5% for the weight-stable group). Of the participants who returned for the follow-up visit, 9 refused to be weighed or did not report their weight and 70 provided self-reported weights through telephone contacts. A separate analysis that included only those participants with measured weights at the follow-up visit showed similar results to the analysis that included those participants who were measured and those who self-reported their follow-up weight. Thus, we present the results that included both the participants with a measured weight and those with a self-reported weight (n = 522). All procedures were performed in accordance with the ethical standards of the Institutional Review Boards of participating institutions; these boards also approved the protocol and informed consent forms.
Data collection and measures
Body weight
The participants' body weight was measured to the nearest 0.1 kg with the use of a standard balance beam scale. The participants were wearing light hospital gowns and no shoes while they were weighed. The scales were calibrated monthly against known weights and were annually certified by the local Department of Weights and Measures.
Weight change and type of weight-change intention
Weight changes were determined on the basis of the definition of a clinically significant weight change, which is a weight change of 5% during a 6–12-mo period (21). At the substudy baseline, the participants who had lost or gained 5% of their measured weight from the preceeding year were asked whether they had been trying to lose or gain weight. If the participant responded "no," the prior weight change was considered unintentional. If the participant responded "yes," the prior weight change was considered intentional. With this information, the weight change of the participants at the substudy baseline was categorized into 1 of 5 mutually exclusive weight-change intention groups: 1) intentional weight loss, 2) unintentional weight loss, 3) intentional weight gain, 4) unintentional weight gain, and 5) stable weight.
Causes of unintentional weight change and methods used for weight loss
Potential reasons for weight changes were ascertained by use of a questionnaire. The participants with unintentional weight changes could choose multiple causes for the change from a provided list, which included illness, surgery, medications, stressful times or events, changes in eating habits, changes in exercise or physical activity, smoking cessation (for participants with weight gain only), and loss of appetite (for participants with weight loss only). The participants who were classified as having intentional weight loss were asked to select the methods they used to lose weight from a list that included changes in eating habits (such as reduced food intake, reduced fat intake, use of fat- or calorie-modified foods), changes in exercise, use of commercial diet products or programs, and consultations with health care professionals.
Subsequent weight change at the follow-up visit
The weight change between the substudy baseline and the 6-mo follow-up visit was calculated as a proportional change of the substudy baseline weight and was then classified into the following 3 groups, which used the 5%-of-weight-change criterion: 1) weight loss (5% weight loss), 2) weight-stable (within ±5% of their substudy baseline weight change), or 3) weight gain (5% weight gain). These 3 groups were used to assess whether the direction of the weight change continued, stabilized, or reversed.
Sociodemographic and weight-related characteristics
At the baseline of the main Health ABC Study, the participants provided information on sociodemographics (age, race, sex, study site, and education) and weight trajectory during adulthood (remained within 10 pounds, gradual weight gain of >10 pounds, gradual weight loss of >10 pounds, marked weight loss and then kept it off, or repeatedly gone up and down again). At the substudy baseline, the participants also responded to a detailed questionnaire regarding lifestyle factors (current smoking and drinking habits) and weight perception (underweight, about the right weight, or overweight).
Health characteristics and hospitalization
At the baseline of the main Health ABC Study, the participants were asked about their past medical history. This history and any medications brought to the clinic visit were used in standardized algorithms to identify prevalent disease cases. At the substudy baseline, the participants' self-reported health status was ascertained by asking the following question: "Would you say your health in general is excellent, very good, good, fair, or poor?" The responses were recoded into 2 groups: 1) good, which included excellent, very good, and good, and 2) poor, which included fair and poor. All overnight acute care hospitalizations since the third annual visit were documented at the substudy baseline, in a manner similar to that used at annual Health ABC Study clinic visits and by telephone contacts made every 6 mo. The primary and secondary diagnoses for hospitalization events were obtained from the participants' medical records.
Statistical analysis
Differences across weight-change groups in means and in proportions of the participant characteristics were analyzed by analysis of variance and chi-square test, respectively. The proportions of subsequent weight-change category by baseline weight-change intention groups were examined by chi-square tests. A logistic regression analysis was used to estimate the odds ratios of subsequent 1) weight gain, 2) weight loss, 3) weight change (the combination of weight gain and loss), and 4) stable weight by the type of prior weight-change intention groups with control for potential confounders, which included age, sex, and race. The weight-stable group at the substudy baseline was used as the reference group. We did not report the weight change for the category of intentional weight gain because only 13 (2.5%) participants reported it, and they all had stable weights at the 6-mo follow-up visit. All statistical analyses were conducted with the use of SAS (22).
RESULTS
Sociodemographic and weight-related characteristics by weight-change intention group
The Weight Change Substudy sample included 22%, 33%, and 45% of the participants who gained weight, lost weight, or remained weight-stable, respectively, during the previous year (Table 1). Although most (89%) weight gain was reported as unintentional, 60% of weight loss was reported as unintentional and 40% as intentional. The participants who intentionally lost weight had the highest mean body weight, had the highest proportion of obesity, and were the most likely to report continued efforts to lose weight. The participants who unintentionally lost weight had a lower mean BMI than did the participants in the other groups and were more likely to report efforts to gain weight. The participants who intentionally gained weight consisted of only 2.5% of the sample, and all either had a normal weight or were overweight. The participants who unintentionally gained weight were more likely to report that their weight had increased gradually during adulthood and were the least likely to be satisfied with their current weight (data not shown); one-third of these participants were trying to lose weight.
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TABLE 1. Sociodemographic, health, and weight-related characteristics of 522 participants by weight-change groups: the Health, Aging, and Body Composition Weight Change Substudy
Health characteristics and hospitalization
Overall, the prevalence of chronic diseases at the baseline of the main Health ABC Study was not significantly different across weight-change groups (data not shown). However, the participants who had a weight change, as either a gain or a loss, were more likely to have reported poor health at the substudy baseline than were the weight-stable participants (Table 1). In particular, the participants in the unintentional weight-loss group were more likely to have reported poor health than were the participants in the other groups.
In the year before the start of the substudy, 17.2% of the participants who were recruited to the substudy had 1 overnight hospitalization. The unintentional weight-loss group had the highest proportion of overnight hospitalization events, followed by the intentional weight-loss group, the unintentional weight-gain group, the intentional weight-gain group, and finally the weight-stable group. During the substudy follow-up period, the participants in the unintentional weight-loss group were the most likely to have a subsequent hospitalization. Compared with other weight-change groups, the weight-stable group had the lowest rate of hospitalization.
Causes of unintentional weight change
The reported causes of unintentional weight gain and weight loss are shown in Table 2 and Table 3, respectively. Changes in physical activity or exercise were the most frequently reported causes of unintentional weight gain, followed by changes in eating habits, medications, stressful time or events, and illness. Illnesses were the most frequently reported potential causes of unintentional weight loss, followed by changes in eating habits, loss of appetite, stressful time or events, and surgery. Most of the participants who experienced unintentional weight changes provided potential causes for the weight changes. Few cases of unintentional weight loss were unexplained.
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TABLE 2. Reported causes of unintentional weight gain1
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TABLE 3. Reported causes of unintentional weight loss1
Methods used for intentional weight loss
The reported methods used for intentional weight loss are shown in Table 4. Changes in eating behavior were the most commonly reported strategy for weight loss, with a reduction in food intake as the most frequently reported change in eating behavior, followed by a reduction in fat intake and then the use of fat- or calorie-modified foods. Another commonly reported weight-loss strategy was an increase in physical activity (13.5%). Only 6% of the participants who intentionally lost weight reported that they had consulted with health care professionals (dietitians or physicians) about their weight-loss strategies.
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TABLE 4. Reported methods used for intentional weight loss1
Subsequent weight changes
Subsequent 6-mo weight changes differed in each group. The participants who unintentionally lost weight gained 1.2 ± 5.4% (
FIGURE 2.. Subsequent weight change in 6 mo by the type of prior weight change and weight-change intention.
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TABLE 5. 6-mo Subsequent weight change of 522 participants by baseline weight change and weight-change intention: the Health, Aging, and Body Composition Weight Change Substudy
The participants in the unintentional weight-loss group at the substudy baseline had the most frequent subsequent weight changes of all the other groups (36.1%). Of the participants who unintentionally lost weight, 22.2% gained 5% of their baseline weight [odds ratio (OR) = 5.33; 95% CI = 2.54, 11.1] and 13.9% continued to lose weight [OR (95% CI) = 2.41 (1.11, 5.21)]. Of the participants who unintentionally lost weight, those who continued to lose weight during the substudy follow-up period tended to have a significantly higher percentage of 1 overnight hospitalizations (33.3%; P = 0.0611) than did the participants who maintained their weight (10.1%) or the participants who gained weight (12.5%) during the same period; however, other sociodemographic characteristics were not significantly different. Of the participants who had intentionally lost weight at the substudy baseline, 15.9% gained 5% of their baseline weight [OR (95% CI) = 3.58 (0.46, 8.79)] and only 4.8% continued to lose weight [OR (95% CI) = 0.85 (0.24, 3.09)]. The proportion of participants with continued weight loss was much higher in the participants who unintentionally lost weight than in the participants who intentionally lost weight, but, because of the small number of participants with continued weight changes, this difference was not significant [OR (95% CI) = 3.25 (0.88, 12.0)].
DISCUSSION
Human and animal studies of the regulation of food intake suggest that older adults have a diminished ability to maintain a stable energy balance and body weight because of age-related alterations in physiology and because of adverse social, medical, and psychological factors that are common later in life (1–3, 5–10). Many of our community-dwelling older participants, however, maintained a stable weight. Furthermore, a significant proportion of the participants who had weight loss or gain at baseline were more likely to maintain the baseline weight or resolve their weight change than to continue to lose or gain weight over the subsequent 6-mo period. Only 3% of our total substudy sample continued to lose weight and only 1% continued to gain weight. Compared with the participants who either had stable weights or intentionally lost weight, the participants who unintentionally lost weight were more likely to continue to lose weight; however, only 14% of the participants who lost weight at baseline did so. This finding suggests that older adults who experience weight loss, even if the weight loss is unintentional, are likely to resolve the weight loss, and the few elderly persons with continued weight loss can be detected with a 6-mo follow-up weight reassessment.
Of note, the participants who had short-term weight fluctuations or instability were more likely to report or to experience poor health status, regardless of their ability to resolve their previous weight changes, than were the participants with stable weights or with no short-term weight changes. This observation warrants continued attention because it suggests that weight fluctuation or instability could be a useful indicator of detrimental metabolic consequences or health problems in older adults.
These findings are similar to the findings reported in small clinical populations, including findings in nursing home patients. In these small clinical studies, most of the surviving older patients who unintentionally lost weight either did not lose any more weight or subsequently gained the weight back after the causes of the observed weight loss were diagnosed and treatment was started (21, 23–26).
In clinical practice, the absence of a single identifiable cause of weight loss is more common in elderly patients than in younger patients, and, when evaluated specifically for weight loss, a significant proportion of elderly patients remain undiagnosed (21). In the present substudy, the reported causes of unintentional weight loss, which included illness, changes in eating habits and loss of appetite, and stressful life events, were similar to the causes reported in previous studies (21, 27). Unrecognized or unexplained weight loss was rare in the present substudy.
Managing older patients with unintentional weight loss remains a challenging task for health care providers. A rational stepwise approach has been suggested for use in clinical practice to establish a diagnosis and to determine management approaches for older patients with unintentional weight loss (23, 24). The guidelines suggest that if the initial basic evaluation does not successfully uncover a diagnosis for the weight loss, then the clinician should establish a management plan that includes a predetermined follow-up in the subsequent 3–6 mo, because some causes of weight loss can be subtle and could be revealed with time (21, 23). We showed that a large proportion of weight loss that occurs in relatively healthy community-dwelling older adults can be resolved in 6 mo, which suggests that a weight-loss management plan for community-dwelling older adults may also need to include a 6-mo waiting period, rather than pursue more expensive and invasive undirected testing as was suggested by Wallace et al (21).
Many of the participants in the present substudy were interested in their weight and were attempting to recover from or maintain their substudy baseline weight change. Older adults who continued trying to lose weight, however, were not successful either in maintaining their baseline weight loss or in continuing to lose weight over the subsequent 6 mo. This finding is similar to the findings of previous epidemiologic studies (28–31), which include a prior report on the Health ABC Study cohort (32). In the Health ABC Study, despite adopting healthier eating behaviors and more active lifestyles, older adults who tried to lose weight did not lose weight; rather, they maintained a stable weight in a 1-y period compared with participants with no weight-loss intention (32). In middle-aged and older men and women, a history of either intentional weight loss or weight loss attempts was a significant predictor of weight gain (28, 30, 31). The intention to change one's weight has been suggested to reflect an overall healthy lifestyle (32, 33); thus, attention to one's weight, regardless of the success of the intended weight change, may foster a healthier lifestyle that helps older adults maintain a stable weight, maintain physical function, maintain a good quality of life, and live longer. It is not yet clear whether attempted weight loss or successful weight loss in older adults is associated with lowered mortality in older adults.
To our knowledge, this is the first study to describe the causes and the natural history of 6-mo weight changes in older adults who were selected specifically because of their weight loss or gain over the prior year. Generalization of these findings to the older population, however, is limited, because the substudy participants were initially selected to have no problems in performing the activities of daily living and to be free from mobility impairment at the time of their enrollment in the Health ABC Study, which was 3 y before the present substudy began. Our participants may have had a better ability to maintain a stable body weight or energy balance than did the persons who were excluded. Also, as with any study that deals with the intent to change weight, the measure of weight-change intention relied on the participants' self-reports, and therefore may be biased. Because older adults who attempt to lose weight are more likely to have weight-related health conditions, caution may be warranted in interpreting the self-reported intent to lose weight (32). These limitations may partly explain why our findings differ from the findings of previous studies that showed that, compared with younger adults, healthy older adults have an altered ability to accurately control their energy balance and to maintain a stable weight after deliberate changes in their diet (1–9).
Notwithstanding, most of the participants in the present substudy had a stable weight or recovered from the baseline weight changes; few of the participants experienced progressive weight loss. As expected, the participants who unintentionally lost weight reported and experienced more health problems and also had a greater risk of progressive weight loss than did the participants in the other groups. These participants were easily identified at an annual exam and with a subsequent 6-mo follow-up.
Older adults who intentionally lost weight reported that they consumed fewer calories and adopted a more active lifestyle to lose weight, which is currently recommended in clinical weight-loss guidelines for adults (34). Although controversy continues as to who should lose weight, who would benefit from weight loss, and how to maximize the benefit from weight loss in older adults, more older adults are trying to lose weight now than ever before (32, 35). Few of the participants in our substudy pursued guidance from their health care providers. In this era of obesity epidemics and ever-expanding diet and weight-loss programs, health care providers should provide appropriate weight-loss guidelines for older adults. Such efforts will help community-dwelling older adults make informed and appropriate decisions on how to control their weight to maximize health benefits and to reduce health problems. More research is needed to better understand the dynamic changes in body weight with relation to weight-change intention and how these weight-change patterns can affect the nutritional and health status of older adults.
ACKNOWLEDGMENTS
JSL and ABN were responsible for the study design. JSL analyzed the data and drafted the manuscript. ABN, TBH, FT, and SBK provided critical revisions of the manuscript for important intellectual content. SMR provided administrative, technical, and logistic support. None of authors had any conflicts of interest.
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