Protein

Protein attracts water and plays an important role in water balance. In cases of severe protein deficiency, the blood may not contain enough protein to attract water from the tissue spaces back into the capillaries. This is why starvation often shows an enlarged abdomen. The abdomen is swollen with edema or water retention caused by the lack of protein in their diet.

When the capillary walls are too permeable, protein can leak out of the blood and settle in the tissue spaces. It will then act like a magnet for water, continuously attracting more water from the blood to accumulate in the tissue spaces.^[9]