Oh Sang-woo
The author is a professor of family medicine at Dongguk University Ilsan Hospital.
“No matter how hard I work out, I just cannot build muscle. I followed every instruction carefully.” It is a complaint heard increasingly often in clinics these days. The growing frustration also reflects the public’s heightened interest in muscle health and strength training. When patients are asked whether they consume enough protein, many quickly respond, “Of course. I make sure to eat it every evening. Then why am I not seeing results?”
Gymgoers work out at the Kolon Sporex fitness center at the Bangbae Open Cultural Center in Seocho District, southern Seoul. [NEWS1]
Muscle is far more than tissue used for movement. It is one of the body’s most important assets for maintaining long-term health. As a metabolic organ, muscle helps regulate blood sugar and maintain a basal metabolic rate, serving as a defense against chronic illnesses such as obesity and diabetes.
Muscle also functions as an endocrine organ by releasing substances known as myokines. These compounds are secreted when muscles contract during exercise and communicate with the brain, liver, fat tissue and immune system. They play roles in regulating inflammation, improving cognitive function and even supporting anticancer activity. Muscle, therefore, represents more than physical strength. It is a central regulator of the body’s metabolic health. Without properly maintaining muscle mass, the body becomes increasingly vulnerable to chronic disease and cognitive decline.
If muscle mass remains unchanged despite consistent exercise, dietary habits should be examined first. Nutrition strategy is just as important as exercise itself. To activate mTORC1, often described as the body’s muscle-building switch, at least 25 to 30 grams (0.9 to 1 ounce) of protein are needed per meal. When protein intake falls below that level, the synthesis process cannot function efficiently.
At the same time, consuming large amounts of protein in a single sitting is not an effective strategy. Excessive intake can reduce absorption efficiency. As people age, muscles also become less responsive to protein stimulation, a phenomenon known as anabolic resistance. This is one reason why simply eating more protein at once does not necessarily lead to better muscle growth. The key lies in consuming moderate amounts regularly throughout the day in order to stimulate muscle protein synthesis consistently.
The most effective protein strategy depends on body weight and fitness goals. For the average adult, 0.8 to 1 gram of protein per kilogram (2.2 pounds) of body weight per day is generally sufficient. Those aiming to increase muscle mass should consume around 1.6 grams, while individuals engaged in intense training or dieting may require closer to 2 grams.
For a 70-kilogram adult performing strength training, approximately 110 to 120 grams of protein per day may be necessary. It is important not to confuse the weight of meat with actual protein content. About 100 grams of meat or fish, roughly the size of a person’s palm, contains only 20 to 25 grams of pure protein. For that reason, experts recommend consuming palm-sized portions of protein-rich foods regularly three or four times a day. This ensures an adequate supply of leucine, an essential amino acid that activates muscle synthesis.
Sleep and rest are just as important as protein intake. Many people assume muscles grow while lifting heavy weights and sweating in the gym. In reality, exercise mainly creates microscopic tears and damage within muscle fibers. The actual rebuilding and enlargement of muscles occur during rest and sleep.
Deep sleep is especially critical because it stimulates the release of growth hormones, which repair damaged muscle tissue and rebuild it stronger than before. By contrast, inadequate sleep raises levels of cortisol, a stress hormone that promotes muscle breakdown. Even with sufficient protein intake, chronic sleep deprivation can undermine muscle growth.
People take endurance tests during the ″9988 Seoul Fitness Field″ event at Yeouido Hangang Park in western Seoul on Oct. 26, 2025. [SEOUL METROPOLITAN GOVERNMENT]
For optimal muscle development, seven to eight hours of quality sleep and at least 48 hours of recovery time are recommended. Muscles damaged through intense exercise require roughly two days to complete the recovery process in which inflammation subsides and tissue becomes stronger than before. Exercising the same muscle groups intensely every day leaves insufficient time for recovery, increasing both the risk of injury and the likelihood of stalled muscle growth.
If muscle gains remain elusive despite hard work, the problem may not be a lack of determination but the absence of a proper strategy. Muscles are not built through exercise alone. They grow only when regular protein intake, deep sleep and adequate rest work together. Building muscle is not about endlessly pushing the body harder. It is about eating properly, resting sufficiently and respecting the body’s natural rhythm of recovery.
This article was originally written in Korean and translated by a bilingual reporter with the help of generative AI tools. It was then edited by a native English-speaking editor. All AI-assisted translations are reviewed and refined by our newsroom.
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