Marasmus is severe undernutrition -- a deficiency in all the macronutrients that the body requires to function, including carbohydrates, protein and fats.They may be stunted in size or have developmental delays or intellectual disabilities.It causes stunted growth in children.Marasmus is a severe form of malnutrition -- specifically, protein-energy undernutrition.Marasmus is a deficiency of all macronutrients: carbohydrates, fats, and protein.People with marasmus are visibly depleted, severely underweight and emaciated.The immune system is also compromised, making undernourished people more prone to infection and illness and slower to recover.When the body is deprived of energy from food, it begins to feed on its own tissues -- first adipose tissue (body fat) and then muscle.Marasmus causes visible wasting of fat and muscle under the skin, giving bodies an emaciated appearance.Prolonged marasmus leads to starvation.What happens to the body in marasmus disease?It also begins shutting down some of its functions to conserve energy.Ironically, marasmus can lead to food aversion.It results from an overall lack of calories.