Abstract and Introduction
Until recently, weight loss in older obese people was feared because of ensuing muscle loss and frailty. Facing overall increasing longevity, high rates of obesity in older individuals (age ≥ 65 years) and a growing recognition of the health and functional cost of the number of obesity years, abetted by evidence that intentional weight loss in older obese people is safe, this approach is gradually, but not unanimously, being replaced by more active principles. Lifestyle interventions that include reduced but sufficient energy intake, age-adequate protein and micronutrient intake, coupled with aerobic and resistance exercise tailored to personal limitations, can induce weight loss with improvement in frailty indices. Sustained weight loss at this age can prevent or ameliorate diabetes. More active steps are controversial. The use of weight loss medications, particularly glucagons-like peptide-1 analogs (liraglutide as the first example), provides an additional treatment tier. Its safety and cardiovascular health benefits have been convincingly shown in older obese patients with type 2 diabetes mellitus. In our opinion, this option should not be denied to obese individuals with prediabetes or other obesity-related comorbidities based on age. Finally, many reports now provide evidence that bariatric surgery can be safely performed in older people as the last treatment tier. Risk-benefit issues should be considered with extreme care and disclosed to candidates. The selection process requires good presurgical functional status, individualized consideration of the sequels of obesity, and reliance on centers that are highly experienced in the surgical procedure as well as short-term and long-term subsequent comprehensive care and support.
With the aging of the population and growing rate of obesity, the prevalence of obesity in older individuals is steadily on the rise. However, it is still mostly viewed as a risk factor for future cardiometabolic disease, not a disease on its own, and is usually studied in younger age groups. Definitions of older age vary across studies and organizations and range from 60 years upward. Most commonly the term "elderly" refers to individuals aged 65 years or older. This review addresses daily clinical challenges in older obese patients.
What is the Definition of Obesity in the Older Population?
Obesity in the older population is usually defined, as in the general population, by a body mass index (BMI) greater than or equal to 30 because of the wide acceptance, simplicity, and relative reproducibility of these measures and despite multiple limitations.[1,4–6] BMI rises with age because of fat mass expansion and decline in spinal height (eg, vertebral compression causing loss of height). BMI-defined obesity misses individuals with "normal weight obesity," mostly abdominal obesity, with diminished lean weight, who, at the older age, are particularly prone to frailty and disability.
Although waist circumference (WC) better correlates with comorbidities, its definition and actual measurement is more variable, and the normal range varies with ethnicity. Fatness (fat mass fraction of total weight) increases with age and muscle/bone mass declines,[8–10] reflecting, in part, lower basal metabolic rate, physical activity, testosterone (T) and growth hormone production as well as the responsiveness to thyroid hormone and leptin.[9,11–13] Assessment of body fat requires equipment such as dualenergy x-ray absorptiometry (DEXA) or bioimpedance-based devices. Further, normal ranges for fat mass fraction vary with sex, age, and ethnicity and may overlap, so its application is complex.
The American Association of Clinical Endocrinologists and American College of Endocrinology suggested a new term and focus, "adiposity-based chronic disease" (ABCD). This diverts clinicians' attention from fat excess per se to its health sequelae, mediated by the mass, distribution, and dysfunction of adipose tissue in the context of its comorbid diseases. Sarcopenic obesity comprises an important phenotype in older adults.[16,17] It is defined by the combination of obesity (according to BMI, WC, or % fat) with impaired muscle strength (< 27 kg and < 16 kg using a hand grip test in men and women, respectively), lower muscle mass (< 5.67 kg/m2 and < 7.23 kg/m2 of appendicular mass index using DEXA for women and men, respectively), and/or impaired physical function. Sarcopenia was recently officially coded in the International Statistical Classification of Diseases and Related Health Problems 10th Revision. Compared to obesity alone, obesity with sarcopenia was associated with higher odds for metabolic syndrome, decreased survival in patients with several cancer types, and osteopenia/osteoporosis.
Obesity is linked to a host of complications and comorbidities that include metabolic syndrome (43% of people aged ≥ 60 years), type 2 diabetes mellitus (T2DM), dyslipidemia, heart failure, atherosclerotic cardiovascular disease, atrial fibrillation, stroke, cognitive decline, many types of cancer, nonalcoholic fatty liver disease, arthritis, thromboembolic events, pulmonary abnormalities, sleep apnea, urinary incontinence, decreased quality of life, frailty, impaired motility, and disability.
Despite the strong link between obesity and metabolic diseases, the "obesity paradox" suggests that obesity may confer some protective effects such as lowering the risk of mortality in older individuals, especially in heart failure or chronic obstructive pulmonary disease patients or in residents of nursing homes. The dissociation between obesity and mortality may be limited to grade I obesity (BMI 30.0–34.9). Low body weight in older people per se is often linked to frailty, undernutrition, or hidden life-shortening disease, the roles of which in the obesity paradox is hard to discern despite attempted adjustments.
Factors That Contribute to the Pathogenesis of Obesity in the Older Population: Practical Aspects
Partly modifiable risk factors for obesity in older age include reduction in energy expenditure due to diminishing physical activity and decline in resting metabolic rate, mostly secondary to declining muscle mass. Age-related muscle loss is accelerated by inflammation, chronic diseases, impaired mobility and nutrition, and declining anabolic hormones (eg, T, growth hormone).[25,26] The decline in resting metabolic rate is estimated at 2% to 3% per year from age 20.
Although monogenic obesity is expressed in early life, family history of early onset obesity in an older individual can provide clues to genetic background, for example, pro-opiomelanocortin and melanocortin receptor mutations. Full exome (next-generation sequencing) testing or obesity gene panels could provide access to developing gene-specific/related treatments (eg, melanocortin receptor mutations). Integration of complex genetic information related to polygenic obesity (eg, contribution by genes such as FTO)[30,31] into the overall care plan in older obese individuals, however, remains a future challenge.
Lastly, obesity is clearly associated with a lower socioeconomic status and financial hardship. Nevertheless, socioeconomic-related factors do not necessarily predict successful weight loss in older patients.
J Clin Endocrinol Metab. 2021;106(9):2788-2805. © 2021 Endocrine Society