Thursday, June 25, 2009

Stemming the polypeptide: Am I eating too much protein?

After I posted my blog with the pasta recipe last week, a Facebook exchange began that turned into a discussion about protein intake.  I had been reading through Chris Carmichael’s book about nutrition for athletes (Food for Fitness) and was surprised to find his recommended protein intake for the bulk of the training season to be pretty low. I had been focusing so intently on reducing my fat intake for the last 6-8 months that it never occurred to me that I should also look at how much protein I was consuming.

As you may recall from a previous post, I take data on my daily food intake using an iPhone application called Absolute Fitness.  I often wonder, as I spend the 10-15 minutes per day that it takes to enter the data, if it is really worth it.  I was thrilled to have cause to actually use this data and decided to make an Excel spreadsheet for my analysis (and, yes, that is a slide rule in my pocket).   I was shocked to find that my protein intake for the last month and a half averaged 111 grams, which equates to 17 percent of my total calories.  It is also close to 0.9 grams per pound of body weight or 1.9 grams per kg of body weight.

So, is this too much?  According to Chris Carmichael and studies performed by others--yes.  Chris Carmichael suggests that during any part of the training cycle other than the “transition” phase (post-focus-race recovery, that is) your intake of protein should be 13-14% of your daily caloric intake.  During transition, you can bump up to 18%. 

Not being one to ever take any one person’s word as gospel, I did a little bit of poking around on the web about protein intake for runners.  This site has a nice, albeit dated summary of studies relevant to the question.  These studies found that elite male runners and other endurance-trained male athletes should strive to take in 0.9-1.4 g protein/kg of body weight.  Other studies suggest that women break down less protein during exercise than men and therefore require less protein relatively speaking in their diets than men.  Remember, mine is averaging 1.9 g/kg!

So why should I care?  First, as an athlete, I know that nutrition affects my performance.  Food is fuel, and we all know when we’re burning biodiesel.  Our emissions smell like French fries. While there is certainly debate about the appropriate ratio of carbs to fat to protein for athletes in various periods of training, the bottom line is that there are tradeoffs associated with opting for more of one over the others.

Since my fat intake has been steadily low, my nutritional tug of war is always between carbs and protein.  Carbs are the primary source of fuel for our bodies during exercise and as athletes, we think about things like carbo loading and taking in carbs during a long run or workout.  If we don’t, we suffer miserably during those long, hard workouts and races.  It took me a while to recognize that eating more protein necessarily means I eat fewer carbs.  This made me wonder about days where I had low energy and whether there was any correlation with protein vs. carb intake.  I wonder…

One other alarming factoid that I found when perusing this subject was an alleged correlation between excessive calcium leaching from the bones with higher protein intake; animal protein in particular.  I found at least one study here that seemed to corroborate this. The authors studied thousands of female nurses and found a significant correlation between fractures (in the forearm of all things) and higher dietary protein intake.  I had no idea that this was an issue and a little more web research led me to believe that perhaps it is not.  

It is irritating to me as a scientist that tenuous correlations suddenly become gospel when they happen to support your personal claim or cause.  The vegetarian community latched on to these studies and turned the correlation between animal protein intake and calcium leaching into fact on numerous websites.  The only scientific studies I was able to find that supported this "fact" were based on loose correlations and certainly could not be used to ascribe any sort of causal link between calcium leaching and protein intake.  I always advise tracking down the original studies to see what the authors actually found rather than rely on a non-scientist’s interpretation.  

I guess I’m still learning the basics here, but I may have mistaken the need for protein for recovery as a need for more protein in general.  This is not the case.  Over the next couple of months I plan to track my protein intake, making sure I’m getting it when I need it (within 30 minutes of completing a workout) but trying to keep my overall intake lower than it has been.  If you have the motivation to do so, you might just track your food intake for a few days and see where your numbers fall.  You might be surprised like me.

NEWS FLASH:  I haven't blogged at all about my training this week, which is going well, thank you.  This is because I'm gearing up to run a surprise race this weekend, though I'm not really trained for the distance.  I will, however, be rubbing elbows with some elite athletes that I really admire!  I can't say more about it, because it's a secret for now.  Look for a post on Saturday evening with a full race report!

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