Sarcopenic obesity may lead to adverse health outcomes in the elderly.
As we age, our body composition naturally changes. For example, we are more likely to gain weight and lose muscle mass, and the distribution of fat mass in our body changes.1: While obesity is increasing among younger members of the population, it is also increasing among older adults. In particular, sarcopenic obesity is increasing among aging adults.2: Although there is still no consensus on the definition of sarcopenic obesity, we do know that it is characterized by low muscle mass and excess fat mass.1,2: Sarcopenic obesity was previously defined as muscle weakness.1: Despite the lack of consensus, health professionals agree that sarcopenic obesity poses a risk for adverse health outcomes in older adults.
Understanding sarcopenic obesity
Researchers recognize the complex etiology of sarcopenia. Sarcopenia was originally thought to be characterized by a measurable difference between fat mass and muscle mass.1: For example, patients were considered sarcopenic when their BMI was greater than 30, or dual-energy X-ray absorptiometry (DXA) was within -1 and -2 standard deviations of a younger cohort of the same sex. eg -1 or -2 with a comparison group of younger women and older women or younger men and older men.3: Sarcopenic obesity was also thought to be associated with hormonal changes that occur with age, low-grade chronic inflammation, insulin resistance, little physical activity, and poor diet.2: More recent definitions of sarcopenia suggest looking at muscle disorders instead of muscle mass. Dynapenic abdominal obesity (DAO) is defined as a large waist circumference and low grip strength.2: Despite the lack of consensus on definitions of sarcopenic obesity, there is agreement on some measures and negative health outcomes.
Age, hormones and inflammation
As we age, we experience changes in our hormone levels, and these changes affect body composition through weight gain.2: Total fat mass is reported to peak between the ages of 60 and 75, while muscle strength begins to decline in the 30s.2: With age, there is a negative correlation between muscle strength and fat mass, such that body weight in the elderly consists primarily of adipose tissue.
Insulin resistance is also a function of aging, along with decreased thyroid hormone levels and increased cortisol levels. Changes in insulin-like growth factor (IGF-1), sex hormones, and dehydroisoandrosterone sulfate have also been implicated in sarcopenic obesity. For example, postmenopausal women experience an increase in adipose tissue and visceral fat as skeletal muscle mass decreases. In men, decreased testosterone levels and changes in the distribution of adipose tissue and muscle.2:
Sarcopenic obesity is also associated with a chronic inflammatory state that negatively affects metabolic function and increases the risk of chronic diseases.2: Fat cells have been found to accumulate in the heart, liver, and pancreas, as well as in the muscles. These accumulations stimulate the secretion of proinflammatory cytokines such as TNFα:, IL-6, IL-1, and leptin, thereby allowing inflammatory cells to infiltrate and cause insulin resistance and lipoxysm. This negatively affects skeletal muscle mass and accelerates muscle degradation. Leptin increases IL-6 and TNF, which in turn decrease anabolism, while decreased IGF-1 and age-related loss of testosterone increase frailty.2:
Adverse health consequences of sarcopenic obesity
As fat mass increases and muscle mass decreases with age, a person’s risk of death, cardiovascular disease, and disability increases.1: For example, the National Health and Nutrition Examination Survey (NHANES),4: sarcopenic obesity has been found to increase the risk of mortality for those aged 50-70 years. Interestingly, the risk of death did not increase in people 70 and older.
2018 study5:00 found that handgrip strength, a measure of muscle quality, was associated with sarcopenic obesity and mortality. When sarcopenic obesity was defined as waist circumference, men with larger waist circumferences had more all-cause mortality.1: Disability (eg, cognition) has also been found to worsen when dynapenic abdominal obesity (DAO) is present. Although only a few studies have examined cardiovascular disease, an association between sarcopenic obesity has been found.1:
Prevention and treatment of sarcopenic obesity
To date, there is no known optimal treatment for sarcopenic obesity. However, nutrition and diet interventions and exercise have shown promise.2: Extreme caloric restriction in older adults is strongly discouraged because of the risks of loss of skeletal muscle mass, bone mineral density, and electrolyte disturbances. Instead, a more moderate caloric restriction (200-750 kcal per day) is recommended.1: Dietary recommendations for elderly patients with sarcopenic obesity include increased consumption of high-quality protein (1.2-1.5 g/kg/day). Protein intake should be carefully monitored in elderly patients with sarcopenic obesity and chronic disease or in poor renal health. The essential amino acids and high leucine content should also be considered as they promote muscle protein synthesis. Vitamin D and calcium should also be considered as part of a nutritional intervention.1:
Physical activity, such as aerobic exercise and resistance training, are also effective strategies for mitigating the risks of sarcopenic obesity. Aerobic exercise can improve a patient’s cardiovascular fitness, and resistance training can help increase muscle mass.1: Any exercise program should be performed under the supervision of the patient’s health care provider to ensure that the program is tailored to the individual’s specific needs.
Although sarcopenic obesity increases with age, there are steps healthcare providers can take to mitigate its negative effects. As mentioned above, diet and exercise can help. Working with older patients with sarcopenic obesity to develop a nutrition and exercise program tailored to their specific needs is a good first step. Although there is a lack of consensus on what constitutes sarcopenic obesity, we do know that there are negative health consequences for older patients who have more fat mass than muscle mass. It is important for healthcare professionals to recognize the risks and work with their patients on a controlled plan to mitigate the associated risks.
- Sarcopenic obesity. an emerging public health problem
- Sarcopenia and obesity
- Sarcopenic obesity. a new category of geriatric obesity
- Sarcopenic obesity and total mortality. Findings from the use of new models of body composition phenotypes in the National Health and Nutrition Examination Survey 1999–2004.
- Association of sarcopenic obesity predicted by anthropometric measures and 24-year all-cause mortality in older men. Kuakini Honolulu Heart Program