When the Rosetta Stone was discovered in 1799, archaeologists finally could decipher Egyptian hieroglyphics because all its inscriptions also were written in ancient Greek - which they understood. Unfortunately, when it comes to decoding nutrition labels, there's no easy way to know what they mean. So here's our rundown of the top three things nutrition labels can tell you, and what they don't.

Calorie count? How food is prepared, how you chew it, and how your gut bacteria behave alters the total calories food delivers to your body. So use the count as a general guide, then establish a healthy diet every day with nine servings of fruits and veggies; four servings (3 ounces each) of animal protein; two or more for grains (only 100 percent whole) and other carbs. Also, if the label says 100 calories, but there are 2.5 servings (250 calories) in the package, beware you don't take in more than you planned!

Trans fats? When the label says 0 trans fats, the food is allowed to contain 0.5 gram per serving! Frequent ingestion may deliver heart-damaging amounts. If the ingredients list includes "hydrogenated oil," that's probably a trans fat (partially hydrogenated oil ALWAYS is). To either, just say no.

Carb counting? Carbohydrate counts include processed carbs and sugars (check the ingredients list for felonious sugar syrups or added sugars). Don't rely on printed carb counts; look for separate info on sugars and fiber, and realize the phrase "whole wheat" or "whole grain" in the ingredients list does NOT mean 100 percent (the only good-for-you form).