Here's the short version:
Stomach growling is caused by stomach acid. You may not feel hungry, but your stomach IS hungry... so it secretes stomach acid...and your stomach starts to growl. When your stomach starts to growl and you're embarrassed and anxious about it, your anxiety causes your stomach to secrete even MORE stomach acid, causing an INCREASE in growling. Got that?
The solution: eat frequent, small meals or snacks with protein and a mixture of complex and simple carbohydrates (complex=pasta, wheat bread, wheat crackers; simple=sugar, jelly)
One more tip: When you're having a growth spurt (ie. if you're a teenager), then your body is wanting more nutrition, better nutrition to sustain your growth. When it's hungry, it's going to produce stomach acid in the hopes that you're going to be feeding it soon. My suggestion: don't eat junk food, eat healthy. Healthy can be a peanut butter and jelly sandwich.
My best wishes for a quiet belly!