Protein powder rules! Halt in the name of growth! Use these 12 guidelines to get the most out of your daily protein shakes

LIFE IS FULL OF RULES.

They guide our behavior, influence our choices and generally make it possible to live in close proximity to one another without. You know, breaking laws. For the most part, living long enough to see adulthood means we've successfully internalized life's most basic rules and managed to obey the most important of them: Look both ways before crossing the street; don't wear a Yankees hat in Boston; keep your hands to yourself unless you ask very, very nicely. But new pursuits come with their own sets of rules that must be memorized before true membership is achieved.

Bodybuilding is one such pursuit: weights before cardio; compound moves before isolation, etc. Yet the sport's most important rules are arguably those involving not the gym but the kitchen.

You've likely already learned that protein is the most important nutrient in the art of building and maintaining muscle, and perhaps you've memorized all there is to know about lean protein sources. If that's the case, you know there's more to protein than chicken breasts, and you won't be surprised that protein powder comes with rules that govern its usage. We've compiled that particular set of rules here to guide you to the perfect physique.

RULE #1

Know when to eat your protein-and when to drink it.

* Without a doubt, the best protein you can get comes from meat - poultry, seafood, beef--eggs and dairy products. That may be a funny thing to say in an article about protein powder, but it's true for good reason. The most basic explanation is that our bodies are built to extract protein from whole-food animal sources, which remain the most natural and best way for us to get the nine essential amino acids that our bodies can't produce. Yet there are times when whole foods aren't the best option for protein, such as: first thing in the morning (Rule 5), before workouts (Rule 7), after workouts (Rule 9), some between-meal snacks (Rule 10) and before bed (Rule 8). Still, the majority of the meals you eat each day should consist of whole-food proteins.

RULE #2

* Whey protein first.

Whey is the most critical protein powder to have in your arsenal. It's the fastest-digesting protein you can buy, which means it's perfect when you need to slam amino acids into your muscles - such as when you wake (Rule 5), before workouts (Rule 7) and after (Rule 9). But the type of aminos it contains is also key. Whey has a high proportion of branched-chain amino acids (BCAAs), the most critical ones for stimulating muscle growth. In addition, plenty of research shows that whey is extremely good at boosting muscle protein synthesis (the process in muscle cells that leads to growth), particularly around workout time. Compounding that is the fact that whey's peptides, or small protein fragments, have been shown to enhance blood flow, which can bring more muscle-boosting nutrients to muscle cells.

So make sure that at the very least your supplement shelf has a jug of whey protein. Look for a product that contains at least some whey protein isolate, which digests more quickly than whey protein concentrate. Feeling a bit flush? Try a whey that contains hydrolysates, which are whey proteins broken down into smaller fragments -- it digests faster than isolate but also costs more.

RULE #3

Casein comes next.

* Think of casein as whey's fraternal twin. They're both derived from milk, but while whey is fast, casein (particularly micellar casein) digests extremely slowly. When a casein shake hits your stomach, it forms a blob that is very difficult for digestive enzymes to break down. Because those hardworking enzymes chip away at the casein blob for a long time (up to seven hours), you get a steady stream of amino acids.

This slow and steady release of aminos has been shown to actually stop the breakdown of muscle that normally occurs when you wait a long time between meals. Since your body needs amino acids at all times to function properly, when you're not eating them (like, say, while you're asleep), your body will chew up your muscles to get them. Casein's ability to halt this catabo-lism is a good thing, and it was traditionally recommended to be taken before bed (Rule 8) and between meals (Rule 10).

New research shows that casein can actually help build muscle in addition to slowing muscle breakdown. One study found that men who drank a postworkout shake containing both whey and casein for 10 weeks gained significantly more muscle mass than men who drank a whey shake. So we suggest adding casein to your postworkout shake (Rule 9).

RULE #4

Don't forget the soy.

* Say you've already purchased a quality whey and a good casein protein powder, and you still have room in your budget - and your cupboard. Your next purchase should be a container of soy protein powder. Hopefully, you've stayed abreast (no pun intended) of the soy controversy, which means you're not buying the old wives' tales that claim soy increases estrogen levels and decreases testosterone levels, In fact, research proves that soy increases muscle mass just as well as whey does, and on top of that, it offers benefits whey and casein don't.