Eat boogers and, if you drop food on the floor, eat that too.
Yep, that comes from a New York Times article that covers how our immune systems are getting weaker due to the use of antibacterial soaps and hand sanitizers.
Basically, your immune system needs germs to practice on and get stronger.
Dr. Meg Lemon, a dermatologist featured in the article says in order to build your immune system “You should not only pick your nose, you should eat it."
If you decide to ignore any tongue-in-cheek humor there and go that route, it might not blow your diet at least.
The website Coole Fitness claims (with no sources listed), a 1/2 cup of snot has 25 calories.