Which condition is primarily marked by weight loss and severe malnutrition in its patients?

Marasmus is a form of severe malnutrition characterized primarily by weight loss and a significant deficiency in caloric intake. It typically occurs when there is an inadequate intake of calories and protein, leading to a drastic reduction in body weight and a marked wasting away of muscle and subcutaneous fat. Patients exhibit extreme thinness and an overall appearance of frailty.

In contrast to other conditions such as Kwashiorkor, which is associated with protein deficiency but may not always present with severe weight loss as the body's fat stores can still be preserved, marasmus distinctly illustrates the effects of both protein and calorie shortfall. The clinical manifestation of marasmus includes not only weight loss but also a lack of energy and a weakened immune response, contributing to the patient's vulnerability to infections.

Pellagra and megaloblastic anemia are conditions resulting from specific nutritional deficiencies—niacin (vitamin B3) in the case of pellagra and vitamin B12 or folate in the case of megaloblastic anemia. While they can lead to significant health issues, they do not primarily emphasize weight loss and severe malnutrition in the same way that marasmus does. Therefore, the defining feature of marasmus is its stark presentation of weight loss and malnutrition, making