Sunday, June 21, 2009

MYTHBUSTERS: Protein Myths

This month's installment of Mythbusters, Fatty Fights Back-style, is all about protein. This is an area where there are tons of myths and misconceptions.

Too much protein

The biggest protein myth is that we can only absorb a certain amount of protein at a time. As the American Society of Metabolic and Bariatric Surgeons says on page 27 of their "ASMBS Allied Health Nutritional Guidelines for the Surgical Weight Loss Patient" document:

There is no scientific basis for this statement.

In fact, it flies in the face of everything we know about macronutrients (protein, carbs and fat), our personal experience and what science tells us when protein absorption is studied directly.

In terms of macronutrients, our bodies were designed to extract every single molecule of nutrition from what we eat. (This is true of most micronutrients, as well, but with micronutrients, there are exceptions.)

Our original ancestors were hunter-gathers and that means they didn't eat what we think of today as a balanced meal. Their diets consisted of stuff they could forage regularly (mostly plant-based foods and, in some locales, fish) and once in a while they killed something big and gorged on meat until it was gone. (They had no refrigerators so they had to eat it all as soon as possible.) So our bodies were designed to process a lot of protein at once.

This is borne out by studies where subjects were given a large "bolus" (scientist-talk for an enormous blob) of protein and then their blood was measured two hours later to see how much of it was digested and got into the body. These studies show that it all gets absorbed.

Finally, we have our personal experience. If our bodies only absorbed 30 g of protein at a time, that means the rest is pooped or peed out and those calories are not stored in our body. So everyone could eat a 16 oz. steak for breakfast lunch and dinner, only absorb 30 g of the protein (120 calories) instead of the 87 g of protein (348 calories) that it contains. What a great diet aide! Except we all know that eating too much meat causes us to gain weight just as much as eating too much of some other food.

Some nutritionist (who should know better) will amend their statement that you can't absorb more than 30 g of protein an hour to say "well, you do absorb it, but it's not all used" or they invoke the dreaded "it will turn to fat!" threat that seems to be so common when talking to dieters.

Now, it's possible that the amount of protein you consume in a day contains more amino acids than your body needs to build muscles and repair body tissues. But that's okay, as long as you are not eating more calories than you burn. If you eat less than you burn, any protein that isn't used to repair muscles and other tissues will be used for fuel, just like the calories from fat and carbohydrates.

Finally, it's not realistic to think that your body will not use anything over 30 g of protein per hour for tissue repair. First of all, even if there is some upper limit, it's going to vary based on individual factors such as body weight, age, and activity level. It won't be the same for everyone.

However, everything I've read and seen tells me that, if your body needs the protien and you give it the protein, it will be used. As an example, body builders routinely down more than 30 g of protein at a time and, the more they down, the bigger their muscles grow. If there was some sort of arbitrary limit, that wouldn't happen.

A related misconception about protein is that you have to be careful not to get too much. Technically, this is true: Too much protein is hard on the kidneys. But "too much" protein isn't going over the recommended RDA. Unless you have some sort of kidney problems, you have to eat enormous quantities of protein for this to be an issue.

In one study, participants ate 2.8 g of protein per kg of body weight with no ill effects. For a 150 pound person that works out to 190 grams of protein! A typical recommendation is to not go over 2 g per kg of body weight though. You can also lessen the impact on your kidneys by drinking more fluid as water helps the kidneys perform more efficiently.

The rest of the protein myths revolve around shakes. There are a lot of misconceptions about protein shakes and the protein used in them. Such as:

You should only consume 100% whey protein isolate - all the other stuff isn't any good.

100% why protein isolate is the most bioavailable, but that doesn't meant any other types of protein are automatically no good. Eggs are more bioavailable than chicken, but no one suggests we shouldn't eat chicken. I say: use the kind of protein that you can stand and don't worry so much.

If you heat protein powder, it breaks down and the protein is destroyed.

Protein powders designed to be used with cold water will clump up if you add hot water. But it's an aesthetic thing, not a nutritional thing. The protein is just fine -- digusting to eat, but still protein.

You can get around this by adding your protein powder to lukewarm water, getting it to dissolve, and then adding the resulting sludge into your hot drink. For baking, just add the powder directly.

Blending your shake breaks down the protein so use a shaker bottle instead.

Once you add liquid to a protein powder, it starts breaking down. This is why you aren't supposed to mix up all your shakes ahead of time. However, blending vs. shaking makes no difference in the process.

You should get all your protein from "real" foods. They are empty calories.

This one isn't a myth so much as it is an opinion that some programs turn into a "rule." It's not an opinion I tend to agree with and I certainly don't think it should be a rule.

First of all, protein supplements are not empty calories any more than a steak is. They can be more bioavailable than a steak too. So they are a good quality protein and they are easy to get down in the required quantities.

Which can lead some people to have problems. Some people don't feel full on shakes and so eat more calories than they should. But lots of people don't have this problem. While most programs don't want you to drink your calories, this really applies more to things like Vitamin Water or juice -- stuff that is mostly sugar and has more calories than it "feels" like it should have. A high quality protein drink is not in the same category at all.

Other people don't like them because they can be full of unnatural ingredients. But there are shakes out there that don't use artificial sweeteners. You just have to read the labels and decide for yourself if a particular shake meets your own standards for what you are willing to put in your body.

So, if a protein shake or protein drink works for you, I say: go for it! If they don't, then don't worry about it; there are other ways to get your protein in.

Some links about how much protein we can absorb:

30 grams of protein in one meal rule

Protein grams per meal
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