Most of us spend a lot of time thinking about our stomachs, but how much do we really know about them? Here's a True/False test to find out:

#1: True or False: Digestion takes place primarily in the stomach. That's False. Gastroenterologist Dr. Joseph Levy says your stomach's main function is to break food into tiny particles called chime. Before sending it to the small intestine where most digestion occurs.

#2: Thin people have smaller stomachs. False. Dr. David Greenwald teaches at the Albert Einstein College of Medicine. And he says that people who are naturally thin can have the same size or even larger stomachs than those who struggle with their weight. They just don't fill it as full.

What about the old idea that eating less shrinks your stomach? Nope. Eating less resets your "appetite thermostat" so you don't feel as hungry, but it won't change the size of your stomach.

This next one's tricky: Sit-ups and abdominal crunches reduce the size of your stomach. That's True AND False. Dr. Mark Moyad is the director of preventive medicine at the University of Michigan. And he says that exercise can't change the size of an internal organ, but toning your abdominal muscles can lead to a smaller waistline.

And our final True/False stomach question: Losing just 2 pounds can prevent acid reflux. According to a University of Maryland study, that's True. As you gain weight, it puts pressure on your stomach, and forces acid into your esophagus. But it only takes a small amount of weight loss to return things to normal. And, since most dieters lose dangerous belly fat first, you'll notice an improvement right away.