Why do the bellies of malnourished children protrude so much?

Protein malnutrition: The protein in our diet is converted to usable aminoacids and plasma proteins that keep fluid inside blood vessels during the bloods transit throughout the body. Malnourished kids leak enema fluid (water) into the organs & tissues because there is not enough protein in the blood to keep it from happening. The kids may look fat, but rather than fat this is water in organs & tissues.

Belly protrusion: The abdomen protrudes due to multiple factors: fluid buidup in the empty spaces in the abdominal cavity due to protein deficiency; accumulation of fat in the livers due to lack of proteins to transport fat away from the liver; and the concurrent exposure in some cases of parasitic infestation.