Loss of muscle mass, known medically as muscle atrophy, occurs when muscle fibers shrink and lose strength over time. This leads to a decrease in muscle strength and size, impacting daily function. Common causes include lack of physical activity, poor nutrition, aging, and certain diseases or medications.
Muscle atrophy can happen slowly over time due to inactivity and the natural aging process. As we get older, muscle fibers shrink in a process called sarcopenia. This normal loss of muscle mass begins around age 30 and worsens after age 60. Staying active with strength training and getting enough protein can help offset age-related declines.
More rapid muscle wasting also occurs with major injuries, immobilization in a cast, or being bedridden. Without resistance from gravity or normal physical movements, muscles begin to rapidly deteriorate. This effect starts within days. Significant muscle loss also happens with chronic diseases like cancer, AIDS, sepsis, and kidney or heart failure.