Obesity in older adults is a public health problem that challenges our health care professionals and health care delivery systems.1-3,10-12
In this 1-year, randomized, controlled trial involving obese older adults, weight loss plus exercise improved physical function and ameliorated frailty more than either weight loss or exercise alone, although each of those was beneficial.
Currently, evidence-based data to guide the treatment of obese older adults are limited.16,17
The few clinical trials that have been conducted typically addressed cardiovascular risk factors rather than physical function.16
However, frailty is an important problem in the elderly because it leads to loss of independence and increased morbidity and mortality.30,31
Physical frailty is common in obese older adults,8,9
and obesity is associated with increased admissions to nursing homes.10-12
Four previous randomized, controlled trials examined the effect of weight loss on physical function in obese older adults,14
but these studies were either short-term19,32,33
or limited to participants with specific health conditions.34
The current study suggests that weight loss alone or exercise alone can reverse frailty but that the combination of weight loss and exercise is more effective than either individual intervention. Therefore, weight loss and exercise may be an important therapy for frail, obese older adults. Moreover, one study has shown that weight loss and exercise reduce knee pain and improve physical function in overweight and obese older adults with osteoarthritis of the knee.34
Our data suggest that a major objective of weight-loss therapy in older adults may be to improve physical function, and we speculate that doing so may be at least as important as treating obesity-associated medical complications, which is often the main goal in treating obese younger adults.35
Physical frailty in obese older adults is associated with low muscle mass relative to body weight (relative sarcopenia) despite a greater absolute amount of muscle mass.4,8
In the current study, relative sarcopenia was reduced in all the intervention groups — owing to the larger reduction in fat mass relative to lean body mass in the diet and diet–exercise groups and owing to the decrease in fat mass and increase in lean body mass in the exercise group. These positive changes in body composition could underlie the improvement in physical function in the participants.4,8
However, because the greatest improvement occurred in the diet–exercise group, adding an exercise program to a diet regimen, which results in the preservation of lean body mass in addition to the reduction in fat mass induced by a diet, may be the best approach. Accordingly, the diet–exercise group had not only the greatest increase in scores on the Physical Performance Test but also the most consistent improvements in strength, balance, and gait.
The improvements that were seen in the objective measures of frailty among the participants in this trial have important implications for the ability of older adults to maintain their independence. The functional items in the Physical Performance Test simulate activities of daily living, and the Physical Performance Test has been used to monitor physical performance and predict disability, loss of independence, and death.20,36,37
Moreover, the VO2peak
relative to body weight is the standard measure for assessing cardiovascular fitness,38
and the VO2peak
is important for assessing the ability to perform activities that require movement of increased body weight.8,39
The improvements in scores on the Physical Performance Test and in VO2peak
among the participants in this study were accompanied by improvements in scores on the Functional Status Questionnaire and in the physical-component summary score of the SF-36 (measuring quality of life), both of which indicate subjective improvements in the ability of the participants to function.
A potential adverse effect of our interventions was the reduction in lean body mass and bone mineral density at the hip in the diet groups. However, the addition of exercise to diet attenuated the losses of lean tissue and further augmented physical function. Although the clinical importance of the modest loss of bone mineral density is unclear, strategies to prevent this loss in participants involved in future studies might include prescribing higher doses of calcium and vitamin D than those used in this study, having participants perform endurance exercise alone or resistance exercise alone (rather than both endurance and resistance exercises), and perhaps antiresorptive therapy. Exercise was also associated with musculoskeletal injuries; careful screening and safeguards before and during exercise are needed to decrease the risk of these adverse events. An additional health concern is raised by findings from observational studies that suggest that weight loss may be associated with an increased risk of death.2
However, these studies did not rigorously distinguish intentional from nonintentional weight loss. Follow-up data from a randomized, controlled trial involving overweight and obese older adults suggest that intentional weight loss may reduce the risk of death.40
The strengths of our study include the randomized, controlled design, the long duration of the intervention, the comprehensive diet and exercise programs, the high rate of adherence to the interventions, and the use of objective and subjective measures of physical function. A limitation of our study is that it was not powered to determine potential differences in the outcomes between sexes. Because we selected volunteers who were able to participate in a lifestyle program, the results may not necessarily apply to the general obese, older adult population. Nonetheless, they provide evidence that successful weight loss is achievable in this population. Further studies are needed to determine whether weight loss can be maintained beyond 1 year and prevent institutionalization of obese older adults. Our sample size was small, and most of the participants were women, white, well educated, and older (70±4 years of age) with mild-to-moderate frailty (and sarcopenic obesity4
), thus limiting broader inferences of our results. Our study did not address the usefulness or safety of these interventions for markedly obese older persons with severe frailty.
In conclusion, our findings suggest that weight loss alone or exercise alone improves physical function and ameliorates frailty in obese older adults; however, a combination of weight loss and regular exercise may provide greater improvement in physical function and amelioration of frailty than either intervention alone. Therefore, weight loss combined with regular exercise may be beneficial in helping obese older adults maintain their functional independence.