Anyone who's tried to buff up his or her body knows the feeling. You're standing in the health food store, staring at aisles and aisles of products -- protein powders, nutrition bars, creatine, amino acids, to name a few -- that promise to make you a muscle god. But which ones do you really need, and how do they work? That, of course, depends on the goals you've set for yourself, what kind of shape you're currently in and any medical conditions you might have (before taking any supplements, it's a must you talk to your doctor and a trainer). But here's a crash course on he supplements you're likely to come across in pursuit of the body beautiful.

Protein Powders: Without a doubt, protein powders are some of the most popular supplements out there. Why, you ask? Because they're (surprise!) packed with protein (some with more than 40 grams per serving) which is absolutely essential to building muscle. But don't let the eye-popping photos of the bodybuilders on the containers fool you, it will take more than a blender to look that good. More than likely, you'll need extra protein in your diet, and chugging a few shakes every day is one way to get it. A few of the most effective kinds of protein powders are made with whey (dehydrated milk), album (dried eggs) and soy (tofu in a powder) protein. And be sure to read the label and take the recommended doses on the can. The best time to take one is right after a workout, but if you're not sure what's best for you, ask a trainer.

Nutrition Bars: If you're looking for a pre-workout energy boost, this is the supplement for the masses. They come in all shapes, sizes and flavors, from chocolate chip to oatmeal raisin and beyond. Along with assorted vitamins and minerals, however, you're likely to get plenty of sugar and some fat and carbohydrates -- so don't skip your Flintstones vitamin in the morning. The sugar goes right to the bloodstream, which can give you a needed lift for a workout, but eat these in moderation, or you'll build your love handles instead of your biceps. Natural foods are always the best choice.

Fat Burners: Do fat burners really get rid of that extra flab? Well, the jury's still out on that one, and there's a lot of controversy swirling around these little capsules. Ask a trainer or doctor before you decide to use one. Perhaps more than any other supplement, there are dangers attached to fat burners. So tread carefully, and be sure to check the labels, too. Most fat burners include one of the following ingredients, for good or bad:
· Chromium: Some experts claim this helps rid the body of fat, but beware, the FDA is still doing studies on the effectiveness of chromium.
· Pyruvate: This is a form of readily available energy. Your body turns sugar into pyruvate, and you'll find it in some fat burners.
· Cayenne: Manufacturers claim this pepper raises your metabolism, thus it's use in some fat burners.
· Kola Nut: Another form of caffeine.
· Uva Ursi and Couchgrass: These are diuretics which drain the water from your body. Losing water does make you lose weight, but water isn't fat, mate.
· Fiver: Both soluble and insoluble, it helps speed the food through the digestion process.

Creatine: Your muscles need bursts of energy to get you through a work out. Creatine, usually in powder form you can mix in water or a shake, battles muscle fatigue. No conclusive studies have been done on its true effectiveness (or long-term safety), but it can cause a loss of potassium in some people, and so you might want to take a supplement or eat a banana. As always, it's best to consult your doctor before you take Creatine (you probably shouldn't take it if you're on any kind of prescription drugs) or any other supplement. HMB: This is an anti-catabolic, which helps prevent the breakdown of muscle. If you're lifting heavy weights, this might be for you. This is popular with bodybuilders and power lifters. It usually comes in capsule form, and you take it with meals. For the chronically skinny, this is one way you can potentially put on some muscle.