What condition is characterized by decreased caloric intake resulting in loss of muscle mass?

Marasmus is characterized by a significant decrease in caloric intake, leading to an overall deficiency in energy and nutrients. This condition typically presents in infants and young children, but it can also affect individuals of any age suffering from severe malnutrition. The hallmark of marasmus is the wasting away of subcutaneous fat and muscle mass, resulting in a fragile appearance. The body is essentially in a state of starvation, leading to the utilization of muscle tissue for energy, which is why muscle mass significantly decreases.

In contrast, kwashiorkor primarily results from protein deficiency despite adequate caloric intake and is characterized by edema and changes in hair and skin pigmentation. Cachexia is a syndrome associated with chronic illness, particularly cancer, and involves unexplained weight loss, loss of muscle mass, and often accompanying inflammation. Obesity, on the other hand, is a condition of excess caloric intake leading to an accumulation of body fat and is the opposite of the malnourished state seen in marasmus. Therefore, the defining feature of marasmus is the direct correlation between decreased caloric intake and the loss of muscle mass.