What to eat—or not to eat—when you have a a cold or the flu.
Chicken & White Bean Soup

Pictured Recipe: Chicken & White Bean Soup

The thinking behind the old saying "feed a cold, starve a fever" goes like this: fasting causes a drop in body temperature, which helps to fight a high fever, while eating raises your temperature, warming you up if you have a cold and keeping your sniffles at bay.

In some regards, starving a fever is sensible: a couple small studies tell us that fasting ramps up the part of your immune system that fights bacteria, which cause some illnesses like strep throat and ear infections. Eating, on the point of feeding a cold, seems to stimulate your immune system to attack viruses like the common cold.

But, unfortunately it's not that simple: fevers can be caused by both bacteria and viruses. The flu, for example, is a virus. And sicknesses like pneumonia may be fueled by either a virus or a bacterium.

We need a lot more research to turn this old wives' tale into a doctor's prescription. So should you eat when you're sick?

Listen to your body. If-or when-you're hungry, eat. And stay hydrated: drinking fluids, especially sipping hot beverages and soups, helps thin out that gunk in your nose and hopefully get it out of your system faster.

Watch: How to Make Classic Chicken Soup