Protein powders are the most common type of workout supplement used today.

I see guys bringing shaker bottles filled with protein to the gym with them all the time. Most drink it after their workouts, although some drink it beforehand too.

So does protein actually help? Well to an extent, yes — but only if you use it correctly and don’t go overboard. Former bodybuilder and current trainer Peter Anthony Hionas summed it up best.

“Supplements (like protein) can help you push yourself over the edge,” Hionas said. “But you have to reach your limit, and get to that edge first, before you should consider any kind of supplement.”

That being said, protein powder can help support a more advanced training and nutrition routine. So here are a few guidelines on how and when to use it effectively. There are two basic types of protein powders: whey protein and casein protein.

Whey protein is popular as a workout supplement because it digests in approximately 20 minutes. It comes from a mixture of globular proteins, which are then isolated from whey — a liquid produced as a by-product of cheese. Whey protein is useful to take around workout time because of its quick absorption. It provides your muscles with a fast nutritional boost.

So, for those looking to pack on a few extra pounds of muscle, try taking 20 grams of whey protein before workouts (on an empty stomach, meaning it’s been at least 3 hours since your last meal) and 40 grams of it afterward.

But remember, 40 grams of whey protein contains about 160 calories. So wait about an hour and a half before eating your next meal — otherwise you could start getting pudgy.

Whey protein can also be useful for people looking to gain definition, or get “ripped,” without losing muscle. When doing intense cardio training routines, you run the risk of your body burning off muscle after all the calories you took in that day are used up. So, before a intense cardio session, try taking a half-scoop of whey protein (about 12 or 15 grams) on an empty stomach about 10 minutes before you work out.

Finally, I’ve had friends in the past ask me if drinking whey protein before bed is a good way to gain mass. It’s not. Whey protein should never be taken before bed. Your body has no use for a quick calorie splurge when you’re about to go to sleep.

On the other hand, casein is a phosphoprotein. It accounts for about 80 percent of the protein found in milks and cheeses, and it digests very slowly — in about six hours.

Casein protein isn’t necessary for people just working out to stay in shape. But, for those looking to gain a lot of muscle mass in a relatively short period of time, casein can help.

When you’re sleeping, your muscles have the best chance to rest and grow for an extended amount of time. Mixing 30 grams of casein protein with eight ounces of skim milk before bed provides your body with some extra nutrients to digest and use for growth while you sleep. A two-pound tub of whey protein runs for around 25 bucks, while two pounds of casein costs about 35 dollars.

So, if you decide to invest in protein powders, try to stick to these guidelines. You want to use it to gain or maintain muscle, not put on unnecessary fat.