As people age, changes in body composition—muscle loss and fat accumulation—are often viewed as a cosmetic concern or a precursor to conditions like diabetes and hypertension. But a new study suggests that these changes may also have profound consequences for lung function.
Researchers at Asan Medical Center (AMC) analyzed data from 15,827 middle-aged Korean adults (9,237 men and 6,590 women, with a mean age of 52.5 years) who underwent abdominal CT scans and lung function tests. Their findings, published in January in Chest, the journal of the American College of Chest Physicians, suggest that lung capacity is tied not just to the amount of skeletal muscle, but to its quality—and to the accumulation of visceral fat.
(Credit: Getty Images)
(Credit: Getty Images)
The study used computed tomography (CT) to segment total abdominal muscle area (TAMA), visceral fat area (VFA), and subcutaneous fat area. Researchers then categorized muscle quality into three types: good-quality muscle (normal-attenuation muscle area, NAMA), fatty muscle (low-attenuation muscle area), and inter/intramuscular fat areas. Low lung function was defined as a forced vital capacity (FVC) and forced expiratory volume in one second (FEV1) below 80 percent of predicted values.
The results showed a clear pattern: more muscle correlated with better lung function, while higher levels of visceral fat were linked to diminished respiratory capacity. In men, lower levels of NAMA and higher visceral fat were significantly associated with poorer lung function. Among women with obesity (BMI ≥ 25), both high visceral fat and low NAMA were correlated with reduced FVC and FEV1. Even in women without obesity, lower-quality muscle was a predictor of lower lung function.
The study highlighted one group at particularly high risk: individuals with sarcopenic obesity—a condition characterized by both muscle loss and excess fat. These patients had a lung function impairment rate nearly four times higher than those with high muscle mass and low visceral fat.
Visceral fat doesn’t just sit in the body—it actively interferes with lung function, restricting lung expansion by limiting thoracic volume and triggering inflammatory responses that compromise respiratory health, according to Professor Jung Young-ju, lead researcher on the study and a professor at the Subdivision of Pulmonary and Critical Care Medicine at AMC.
“In men, lower-quality muscle and higher visceral fat were both linked to poor lung function, while in women, the impact varied depending on whether they were obese,” she said.
Professor Jung Young-ju (left) of the Subdivision of Pulmonary and Critical Care Medicine and Professor Kim Hong-kyu of the Subdivision of Endocrinology and Metabolism, both at Asan Medical Center (AMC), led a study linking muscle quality and visceral fat accumulation to lung function decline. (Courtesy of AMC)
Professor Jung Young-ju (left) of the Subdivision of Pulmonary and Critical Care Medicine and Professor Kim Hong-kyu of the Subdivision of Endocrinology and Metabolism, both at Asan Medical Center (AMC), led a study linking muscle quality and visceral fat accumulation to lung function decline. (Courtesy of AMC)
Those in the highest quartile for NAMA had significantly better lung function, with FVC and FEV1 percentages up to five percent higher than those in the lowest quartile. Conversely, individuals with the highest visceral fat levels had FVC values that were, on average, five percent lower than those with the least visceral fat.
The study also explored the role of myosteatosis—the accumulation of fat within muscle tissue—which has been linked to reduced muscle strength and chronic inflammation. Researchers found that myosteatosis could be an overlooked factor in declining lung function, particularly in women without obesity.
“Improving lung function may require tailored management strategies that focus on reducing visceral fat and enhancing skeletal muscle quality,” Professor Jung said. “For women without obesity, muscle quality alone was a key factor, which suggests that interventions need to be adjusted based on an individual’s body composition.”
Professor Kim Hong-kyu of the Subdivision of Endocrinology and Metabolism at AMC, who co-led the research, added that a one-size-fits-all approach won’t be effective. “For people with obesity, a combination of aerobic and strength training is ideal,” she said. “For those who aren’t obese, the focus should be on enhancing muscle quality, not just muscle mass.”
The findings suggest that lung function decline may begin earlier than previously thought, driven in part by changes in body composition. Chronic lung diseases such as COPD have long been associated with aging, but this research suggests that the risk factors start accumulating decades before symptoms appear.
"People assume sarcopenia and visceral fat accumulation are problems that show up in old age,” Professor Jung said. “But by the time someone is diagnosed with lung disease, the damage may already be done. Prevention needs to start much earlier.”
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Kim Ji-hye jkim404@docdocdoc.co.kr
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