Peri-Workout Nutrition, Part II:
To Carb or Not to Carb
In Part I of this article, I discussed some options for pre- and intra- workout nutrition and supplementation. The key word here is some. These are not the only options, just a few that I have found to be particularly interesting and useful for myself and my clients. When you think post-workout nutrition, you probably think protein and fast-acting or simple carbohydrates, but why? Because you probably overheard some bros saying that you have to refill glycogen stores post-workout. Since we are the country that loves to overeat and eat carbohydrates all day long, I can imagine that the thought of empty glycogen stores may be scary. But keep in mind that thousands of years ago there were not McDonald’s® and a Subway® on every corner.
Low glycogen stores were normal, Honey Boo Boo type physiques were not. So, I assure you that you can survive periods of glucose deprivation and, in fact, you can benefit from these periods as well.
I’m going to discuss two schools of thought on this issue: to immediately carb-up post-workout or to prolong or completely avoid carbs post-workout. I think we are all aware that exercise increases insulin sensitivity, so the post-workout meal is the perfect time to take advantage of this by eating carbs, right? Not necessarily. I’m not particularly vested in either protocol, so I will simply break down both methods and then it is up to you to decide which is best for you.
I don’t know about you, but I lift to increase muscle mass in hopes of looking like Arnold in Commando, not that skinny kid with painted on abs in Twilight. Assuming you have your workout in check, you then need to focus on proper nutrition to trigger protein synthesis and limit muscle protein breakdown. Before you start cursing protein breakdown, just realize that our body’s ability to break down and rebuild tissues is quite incredible and useful. Usually when this is discussed, you’ll see some little equation where you need muscle protein synthesis to be greater than muscle protein breakdown in order to have optimal net protein balance. I hate math and equations so I’ll spare you. However, I think we can understand that we want more protein synthesis than protein breakdown, that’s pretty self explanatory. Protein intake is a must to stimulate protein synthesis, now let’s delve into carbohydrates.
It was once thought that we needed carbohydrates post-workout to help initiate muscle protein synthesis. However, in a study by Koopmen et al. they found that “co ingestion of carbohydrate during recovery does not further stimulate post exercise muscle protein synthesis when ample protein is ingested.”  Here’s a table showing their data:
The figures above compare whole body protein breakdown, protein synthesis, oxidation rates, and net protein balance.  Three groups were given a protein, protein + low carb, or protein + high carb feeding after 60 minutes of resistance exercise. As you can see, there really was no benefit in the carbohydrate + protein vs protein alone. Now, proponents of carbs post-workout will counter by saying something like, “yes, but insulin inhibits muscle protein breakdown so we need those carbs for a better net balance.” But let’s not forget that all foods increase insulin to some degree and whey protein actually to quite a high degree. In a recent study by Albert Salehi and colleagues, they tested the insulinogenic response of whey (16.7g protein) vs. white bread (3.7g protein). They concluded that the whey caused a greater increase of postprandial insulin than the white bread.  So insulin does seem to play a crucial role in this process, which is one of the reasons that pro bodybuilders find it so useful. Hyperinsulinemia, or high levels of insulin, were shown to further stimulate protein synthesis during times of hyperaminoacidemia or excess levels of amino acids.  This happens due to insulin’s role in inhibiting muscle protein breakdown. There are also other beneficial nutrient repartitioning effects of whey vs. sugar in the insulin response they generate, which I will touch on at another time.
So in plain English, carbohydrates are not needed post-workout to initiate protein synthesis as long as protein intake is adequate. Insulin, however, is important because it prevents the breakdown of muscle. What level does insulin need to be at? A study by R. J. Louard and colleagues found that insulin levels of 15-20 mU/L are sufficient enough to elicit a decrease in protein degradation and that 25 mU/L is about as high as you would need to go before there would be no further benefits.  So even if you don’t want to use whey protein, high levels of protein can still increase insulin to a high enough extent to reap the benefits. Even leucine alone generates a rather large spike in insulin.
The benefits of prolonging the carbohydrate intake are increased insulin sensitivity and increased fatty acid oxidation (fatty acids broken down for energy), both helpful in body recomposition. Not to mention, glycogen stores should be somewhat depleted, the body will attempt to increase these via gluconeogensis (which requires energy). And if you recall from my last article, during periods of glucose deprivation, AMPK is stimulated which plays a role in fat burning. The leucine and protein will be present to ensure optimal muscle protein synthesis. Try eliminating the carbs from your first post-workout meal and you will see that it’s helpful in your pursuit of leanness.
The other side of the argument is that you want to take advantage of the increased insulin sensitivity immediately following your workout, and those carbs ingested will likely go to muscle tissue and not be converted to fat. This sounds great in theory, but why would your insulin sensitivity be any less if you waited a few hours to have your carbs? If anything, insulin sensitivity would increase further and lead to even better nutrient repartitioning. As mentioned earlier though, glucose deprivation does activate AMPK which will inhibit mTOR (inherently anabolic), but your body will still aim to maintain a certain level of blood glucose and should be able to do so with the large amount of protein + fat consumed. So as you see, there are pros and cons to both.
To lose FAT:
I propose waiting to have your carbohydrates post workout. How long? At the very least, wait until your second post-workout meal. You could go so far as to wait until your final meal of the evening or breakfast the next day. If you wait until the following day, and you plan to lift that day, then you should “carb-up” for your workout to ensure that you have plenty of energy for an optimal session. If you are going to prolong the carbohydrate feeding, make sure you are taking in ample amounts of protein and moderate to high amounts of fat depending on goals.
To gain MUSCLE:
I still think you could benefit from holding off until that second meal, especially if you are eating carbohydrates pre-workout. Fatty acid oxidation and insulin sensitivity are useful tools in any diet, whether for mass or getting lean. If you eat a good amount of carbs up until your lift, what would the purpose of pounding down more carbs post-workout be? Regardless, your caloric goals are still of importance. But since your main concern is growth, I don’t think immediately ingesting carbohydrates would hurt, it just won’t be as good for losing fat. In fact, you can get away with simple carbohydrates here because insulin sensitivity is increased. Some people like chocolate milk, sugary cereal, apples, or dextrose type shakes. We can argue about which source is better, but there’s really no research that says one is exponentially greater than the other.
What can you take away from this research? I think we learned that post-workout carbs aren’t technically a must have. If you love your post-workout protein + carb shake, then don’t change it. If you want to try and improve body composition a bit, then give the no carbs post-workout a shot. The most important post-workout must haves in my opinion are leucine and protein. If you can take your leucine first and then have the protein 10-20 minutes after, it would be ideal. I will touch more upon that in another article. Also, when I cite studies, I am in no way saying they are gospel. They are simply tools for us to use in furthering our understanding of how our body works. Try to be open-minded and realize that there are multiple ways to achieve the same goal.
 Koopman, Rene, and Milou Beelen. “Coingestion of Carbohydrate with Protein Does Not Further Augment Postexercise Muscle Protein Synthesis.” Http://www.the-aps.org/. American Journal of Physiology, 3 July 2007. Web. 22 Oct. 2012. <http://ajpendo.physiology.org/content/293/3/E833.full>.
 Salehi A, Gunnerud U, Muhammed SJ, Ostman E, Holst JJ, Björck I, Rorsman P. The insulinogenic effect of whey protein is partially mediated by a direct effect of amino acids and GIP on beta-cells. Nutr Metab (Lond). 2012 May 30;9(1):48.
 Gelfand RA, Barrett EJ. Effect of physiologic hyperinsulinemia on skeletal muscle protein synthesis and breakdown in man. J Clin Invest 80: 1–6, 1987..
 Louard, R. J., D. A. Fryburg, R. A. Gelfand, and E. J. Barrett. “Insulin Sensitivity of Protein and Glucose Metabolism in Human Forearm Skeletal Muscle.” Department Of Internal Medicine, Endocrinology Section, Yale University School of Medicine, New Haven, Connecticut, n.d. Web. 19 Oct. 2012. <http://www.ncbi.nlm.nih.gov/pmc/articles/PMC443389/pdf/jcinvest00054-0210.pdf>.