A poor person's life is a dangerous one. Without money to buy enough food, a poor person can easily fall into a potentially fatal downward-spiralling trap of undernutrition and sickness.
Poor nutrition lowers the body's resistance to illness, and illness aggravates poor nutrition.
Cells need protein and calories to grow. Without them, essential tissues and processes cannot develop properly. Among the tissues affected by undernutrition are the mucous lining and muscular wall of the intestine. If these are weakened, food is not absorbed efficiently. In addition, undernutrition may lead to slower production of antibodies and white blood corpuscles, resulting in lowered resistance to infection.