In the article "How Much Carbohydrate, Protein and Fat You Need To Stay Lean, Stay Sexy and Perform Like A Beast," I discuss the health importance and positive performance implications of moderating carbohydrate intake. It's also extremely apparent that fatty acids are the slow burning fuel preference of the human body during endurance, aerobic activity, and also crucial for cell membrane health, hormones, brain and nervous system performance.
But how about protein? Where does that fit in? In this article, you're going to discover exactly how, and also how to eat the proper amount of protein, and why you as an endurance athlete probably need way less protein than you think.
How Much Protein Do You Actually Require?
When it comes to protein for athletes, you've no doubt heard these same recommendations over and over again:
"Athletes need more protein."
"Protein is crucial for muscle repair and recovery."
"Eat plenty of lean protein."
Phrases such as this get thrown around as gospel truth sports and exercise nutrition, but the problem is this: While you certainly do need amino acids from protein for repair and recovery, neurotransmitter formation, avoidance of muscle wasting, etc., the importance of protein is often blown way out of proportion.
Let's start here. To determine how much protein you actually should be getting, you need to be familiar with an important term called "nitrogen balance," and here's how nitrogen balance works:
Nitrogen enters your body when you consume protein or amino acids, and nitrogen exits your body in your urine as ammonia, urea, and uric acid, which are all breakdown products of protein. When the amount of protein you eat matches the amount of you use, you're in nitrogen balance.
As you can probably guess, if you don't eat enough protein, you'll be in negative nitrogen balance and unlikely to be able to repair muscle after a workout. This is called a "catabolic" state. If you consume too much protein, you'll be in positive nitrogen balance, and while you'll have what you need for muscle repair (an "anabolic" state), there can be some health issues that arise when you achieve too positive a state of nitrogen balance. This is because your body can get overfilled with ammonia, urea and uric acid, which, aside from the impact on your aging and longevity, can also have some nasty side-effects that we'll get into in just a bit.
The current U.S. recommended dietary allowance (RDA) is 0.36 grams of protein per pound of body weight per day (0.8g/kg), and this amount is necessary for the average person to be in nitrogen balance without protein deficits or protein excess. While athletes and frequently exercising individuals need more protein than this, you'll frequently see bodybuilders, football players, weightlifters and other big strength and power athletes taking this to the extreme and consuming far in excess of this protein RDA (in some cases up to 2 grams per pound!). Unfortunately, this high amount of protein seems to be catching on in endurance sports too.
However, studies suggest that whether you're a strength or an endurance athlete, there really isn't much additional benefit of exceeding 0.55 grams per pound of protein (1.2g/kg) if you want to maintain nitrogen balance. If you're trying to exceed nitrogen balance for the purpose of putting on muscle or recovering from more extreme exercise sessions, studies also indicate that you don't need to eat more than 25 percent above that 0.55 g/lb, which would be 0.55×1.25, which is 0.68 g/lb, or 1.5g/kg. For simplicity, you can just round that up to 0.7 g/lb (35).
So let's put those numbers into context. I weigh 175 pounds. If I don't want to gain muscle, and I just want to make sure I'm getting enough protein for muscle recovery and body repair, I should eat a minimum of 0.55×175, or 96 grams of protein.
Rounded up to an easy number of 100 grams, that means I could have a couple scoops of protein powder with my morning breakfast, a can of sardines over my salad at lunch, and 4-6oz of grass-fed beef with dinner. That's easily 100 grams, and doesn't even count the other protein I get from seeds, nuts, grains, legumes, etc. If I'm eating about 3200 calories a day, which is a typical calorie intake for me, that puts my protein intake at about 13 percent.
Frankly, this is about exactly what I would eat on an easy exercise day. The rest of my diet is comprised of healthy fats along with large amounts of plants and light amounts of fruits.
And if I wanted to gain muscle or I have a day on which I'm doing a large amount of muscle damaging exercise such as a long, hard run, I would eat 0.7×175, or about 125 grams of protein. So I would basically just add in a couple handfuls of raw almonds and a dollop of full fat yogurt, or a couple extra scoops of protein powder and I'd be good to go. In terms of macronutrient percentages, this would come closer to about 16 percent of my daily calorie intake.
What Happens If You Eat Too Much Protein?
So what are the actual risks of eating excess protein, or having your nitrogen balance too high?
First, consider that, as referenced earlier, ammonia is a toxic compound to the body. Once you get close to about 1000 calories a day of protein (that's about 250 grams), you can no longer convert ammonia to urea, and you begin to build up this toxin within your body. This is extremely stressful on your internal organs, especially your kidneys.
Next, excess protein can cause dehydration if you do not drink enough water. This is because your kidneys need more water to convert ammonia into urea.
Finally, mammalian target of rapamycin (mTOR) is a gene in your body that is directly correlated to accelerated aging. Decreased activity in this gene can be caused by moderate caloric restrictions and slightly lower amino acid intake. So excessive protein intake and a constantly positive nitrogen balance could actually shorten your life!
Could Too Much Protein Be Making You Age Faster?
Let's delve into that last point in even more detail.
It turns out that over 75 years of human longevity research and recent findings have revealed a metabolic pathway which gives us a perspective on protein that, together with insulin, can influence reproduction, aging, and susceptibility to degenerative disease and even cancer. A scientist named Cynthia Kenyon (look her up!) had important work back in the mid-1990's that revealed conclusively that the minimization of insulin is the single most important factor toward the enhancement of longevity and health. Tawnee Prazak, host of Endurance Planet, got into this insulin topic with me on a recent episode. Cynthia's work shows the primary reason that caloric restriction actually works so well for anti-aging.
But it turns out there's another reason that caloric restriction and protein fasting seems to confer such a marked improvement in health and longevity, and it's the mTOR metabolic pathway I mentioned earlier. mTOR belongs to something called the P13K pathway, which is activated by insulin, nutrients and growth factors. It turns out that keeping mTOR down-regulated by fasting and by limiting protein intake to what is simply necessary for maintenance is a key to maximizing cellular repair and regeneration and immune function, thus enhancing longevity and minimizing the risk of chronic disease and cancer. When paired with maintaining low insulin levels by avoiding frequent high carbohydrate and protein related blood sugar spikes, keeping the mTOR pathway largely down-regulated helps keep disease at bay and helps keep you young.
Now don't get me wrong -- you don't want to completely shut down mTOR pathways, because it is intimately involved with recovery, growth and reproduction. If you are seeking conception and pregnancy, doing extreme work loads, performing high level athletic training or are a child in the critical growth periods from infancy through adolescence, continually limiting protein and mTOR can be less desirable. Hence my recommendation for 0.55-0.7 g/lb of protein as a helpful range. But even if you're an athlete, you should have times that you recover and consume less protein, and you should certainly consider avoiding 0.7 g/lb. If you're concerned about satiety, just remember that research shows healthy fat to be just as satiating as complex carbohydrates or high protein loads.
Summary
The take-away message is this: Eat as much protein as your body needs for repair and recovery (about 0.55g/lb) eat a little more if you want to put on muscle (up to 0.7g/lb), and then take in the rest of your calories from healthy fats and vegetables, with limited amounts of fruits and natural starches such as sweet potatoes, yams, white rice, quinoa, amaranth, millet, etc. for fueling more intense bouts of physical activity.