
21. Your Immune System May Deteriorate
You rely on your immune system to keep your body safe from nasty germs that come in and can make you sick. Protein is a critical building block of the antibodies your body makes to fight off those germs, so if you do not get enough, you will be unable to produce enough antibodies (via Eating Well). The result is that you may quickly become sick, and something as simple as a cold can knock you out for days (via Men’s Journal).