What is it about nutrition that makes everyone think he/she is an expert? Here is one of my typical discussions.
Big Larry On the Bike (BLOB): With the kilometers we do, we really need to eat two protein bars during the day to get enough protein.
Me: Oh ya, why is that?
BLOB: It is just too hard to get enough protein without eating protein bars.
Me: Really, how much protein do we need?
BLOB: More then what you can get in your diet.
Me: Well, what if I told you that endurance athletes don't necessarily need to compensate for protein because with a normal diet they already get more then enough.
BLOB: You obviously don't know anything about nutrition and your obviously reading the wrong magazines.
Me: What if I told you that a study we just published in a peer reviewed scientific journal, not a magazine, says that the timing of the protein could actually be more important than how much you have.
BLOB: Like I said you don't know anything about nutrition.
Me: What if I told you that I have a research program that specifically looks at protein metabolism in the muscle and that if you can tell me whether an essential or non-essential amino acid activates the mTOR signaling pathway, I will concede that you are indeed the expert and I do not know anything.
BLOB: m-who…essential what...you still don't know anything about nutrition.
…And so it goes. This is exactly why I hesitate to write on matters related to nutrition. People tend to get blinded to what is fact and what is fiction because of powerful marketing forces. Also, there are many people passing off nutrition advice based on what they read in magazines and on the web, which we all know to be 100% true and accurate. Finally, the fastest guy in the peloton or the biggest guy in the gym are usually counted on as a reliable sources when in reality they got that way because they have great genes and would end up that way no matter what they did. The truth is that unless you are on a caloric restricting diet or very unbalanced diet, you are probably getting enough protein in your diet. The daily recommendation for the general population is 0.8 g/kg/day. So, for an average 70 kg person that equates to 56 grams of protein a day. If an average person is eating 2,500 kcal (10,500 kJ), that is just under 10% of their daily caloric intake. For endurance athletes, we sometimes push this recommendation up to 1.6 g/kg/day even though not all the data is in agreement or supports this higher recommendation. So, if you are 70 kg that equates to 112 g of protein per day, and if we consider a 3,500 kcal diet (14,700 kJ) which is more likely in an endurance athlete, that is still only 13% of your caloric intake.
As you can see, these numbers are not hard to achieve on a well balanced diet. It is worth mentioning though that a recommendation for an absolute amount of protein (g/day) is only half the story. In reality, these numbers can change based on whether you are eating enough energy to match what you are expending. This is easy to comprehend if you consider that the main job for protein in the body is to make and rebuild structures. This making and rebuilding are the repair and adaptation processes. The process of making structures in the body requires energy, and if you do not have enough energy, protein does not build these structures very well. So, for protein to do its job it needs enough energy. Second, protein can be a source of energy and since athletes expend more energy, they may need more protein. However, protein is used for energy only when other sources (fat and carbohydrate) are in short supply. So, if you have enough other sources of energy, protein is not used. There is actually evidence that since athletes are more efficient at using their energy sources, protein is used less and therefore less is required in the diet. What this means is that if you are eating enough calories to match what you are expending, there is actually very little reason to approach the higher 1.6 g/kg/day.
After exercise and protein feeding
So what is the deal with timing that I referred to earlier in my discussion with SLOB? As stated, the main job of protein is to build up structures in your body. To be more accurate, when we eat protein it is broken down into amino acids and these are used to build proteins in the body. Your muscle is in reality a large chunk of different proteins assembled in a way that allows them to do work. When we stress our body, the body adapts in a way that allows it to do that work better next time. That adaptation is accomplished by building the proteins that allow it to work better and getting rid of the proteins that do not help. That is why weight lifting makes you bigger (more proteins for stronger contraction) and endurance training does not make you bigger but makes you more aerobically fit (more proteins for aerobic energy production). So, after exercise our body is in a state where it wants to adapt to what it just did. Certain cellular machinery is saying, "ok, we need to make these proteins to help us for next time." If we do not provide the amino acids and energy to make those proteins, the signal is kind of wasted and the response is minimal. However, in that period after exercise if we do provide amino acids and energy, then the body can build up those structures so that we take full advantage of the process that was stimulated. This timing of nutrition has become a large area of research. It allows people to take advantage of key anabolic periods. So, by timing your protein at the right time, you get a much bigger bang for the buck.
The next question is how much protein do we need? Again, this is probably less than most believe. Current evidence shows that this can be accomplished on 6-8 gm of essential amino acids, which equates to less than 20 grams of protein. Remember though that energy is also needed for these building processes, which means that carbohydrate is needed and since carbohydrate is still the main macronutrient of cycling, and glycogen stores are our main concern, protein should never come at the expense of carbohydrate. Twenty grams of protein is not a huge amount and can be accomplished with real food. For instance, a smoothie made with yogurt, fruit, and honey is a perfect recovery drink and when given a choice, fresh, whole food provides far more "other nutrients" that we need. But, it is worth mentioning that shakes and bars do have their place. Shakes and bars often represent an easy and convenient way to take your food with you, or to get a lot of energy and protein down at once. A shake or bar advertising the largest amount of protein is not necessarily what you are looking for though, because a lot of that protein will essentially be lost in your urine. Your body can only process so much protein at once. Most regular energy bars have a good balance of protein and carbohydrate and therefore do not need to be special recovery formulas. Finally, at the end of the day the one that you will actually eat will be the most effective because no bar or shake works if you do not eat it.
So, do we need to go out of our way to eat extra protein during the day? No, especially if we are eating enough energy to balance our expenditure. Does protein have its place with endurance activity? Definitely, we need it to rebuild and adapt to our activity and this is most important immediately after exercise but should not come at the expense of carbohydrate. Does this require special shakes and bars? No, real food is always better when given the choice, however, bars and shakes do offer a convenient and easy way to make sure we get what we need.
Ben Miller is Senior Lecturer in Exercise Physiology. Ben did a PhD at the University of California – Berkeley and a Post-Doc at the Institute for Sports Medicine, Copenhagen before arriving in New Zealand. As a departure from his life in a closed scientific box safe from the realities of the world, he is a cyclist regularly taking his life in his own hands on the streets of Auckland and in the local club racing and criteriums. Ben's wife is much more successful at cycling having competed full-time in Europe and the US for the last 4 years