Written by Nick Shaw
Seemingly everywhere on the internet, carbohydrates (carbs) are under attack as being evil, wicked, foul and even sinful. I mean heck, even LeBron James was on a low carb diet. Surely, carbs must be the root of all evil! You have Paleo, the Atkins diet, South Beach and the Zone diet, to name a few of the more popular diets, that put a premium on restricting carbs. Some out there would have you believe that eating carbs is a surefire way to become obese, or at the very least a good way to prevent you from getting lean(er). The purpose of this article is to help shed some light on the positive role that carbohydrates play in a person’s diet and even more so in the role of the serious athlete’s diet.
Why Low Carb Diets are Appealing
Before we dive into the benefits of carbs for athletes, we must take a look at why low carb diets are so popular in the first place. This is mostly due to low carb diets getting such great results very quickly in terms of overall weight loss. Notice that I did not say fat loss or tissue loss, just bodyweight loss. Low carb diets are great at helping people drop weight very rapidly.
It’s not uncommon for somebody that is not used to a low carb diet to drop anywhere from say 3-5 lbs or more in the first week. This accelerated weight loss is mostly the result of losing water weight and “bloat” and, not necessarily a decrease in actual tissue. If an individual has had bad luck with losing weight most of their life, seeing those quick results is incredibly appealing. Let’s face it; we live in a society where people want instant results and instant gratification. This makes low carb diets wildly popular. Many people get caught up in the short run when it comes to dieting and don’t see the larger picture of what will happen many months or even years down the road with these types of fad diets.
From my personal experience of speaking with CrossFitters all over the country, they’ve all tried Paleo and saw great results at the start. What happens with nearly all of them is that over time, the success stops and their strength/performance begins to suffer in the gym. When that occurs, coupled with their weight not budging, many become discouraged.
A discouraged dieter will quite often trend back to their starting weight; they are no longer seeing the results that they were used to and begin to engage in old food habits. Not only does the slowing of results become discouraging, but the carb cravings tend to increase as well, continuously tempting the dieter. In the long run, lower carb diets are very hard to sustain. If a diet isn’t sustainable, that’s a BIG red flag!
It’s also important to note here that I’m not entirely against lower carb diets in general. In fact, I think they have a host of benefits to the general population. For example, if my mom were to ask me for a diet, I would surely recommend a lower carb diet to her (Hi mom!). A diet like Paleo that is rich in lean proteins, healthy fats and vegetables is a great starting point for a lot of individuals, especially those that are less active. However, where low carb diets really fall short is for athletes and anybody looking to improve their strength or performance. Athletes looking to get stronger or leaner and grow more muscle need to examine the potential positive impacts that carbs can have on their diets.
Why Athletes Need Carbs
(I’ve taken much of the following straight out of “The Renaissance Diet” book)
1) Supplying the Nervous System with its Preferred Fuel
Carbs (via blood glucose) are the overwhelmingly preferred fuel of the nervous system. Well-maintained blood glucose levels resulting from a diet adequate in carbohydrate allow for optimal nervous system function, which means better muscle recruitment, more fatigue resistance, and even more workout motivation. Much of the fatigue of long duration training is nervous-system mediated, and actually not a result of local muscular factors (legs themselves getting tired, for example). Providing the nervous system with an adequate source of blood glucose is important towards optimizing workout intensity and duration.
2) Refueling Glycogen Stores
In addition to glycogen’s role as a provider of energy for high intensity workouts, its storage in the muscle plays a role in the regulation of muscle protein synthesis (growth). Low levels of glycogen by themselves have been shown to feed into a cellular signaling cascade which results in the downregulation of muscle growth. That is, just HAVING low muscle glycogen levels, irrespective of training intensity, can damper muscle gain and increase the risk of muscle loss. Since dietary carbohydrate is such a dominant determinant of muscle glycogen, having low dietary CHO (carbohydrate) can have a direct negative impact on muscle growth.
3) Secreting Insulin
When carbohydrates are eaten, insulin is secreted proportionate to the amount of carbohydrate that appears in the blood after digestion (in non-diabetic individuals). The more carbs eaten, the more insulin is secreted, and vice-versa. Insulin, a hormone secreted by the pancreas, has a profound effect on muscle growth. That is, when insulin is secreted into the blood and binds to target receptors on the muscle cell’s surface, a cascade of chemical messengers turns the cell’s muscle-growth machinery up to a reflectively large extent. Because of the powerful anabolic effect of insulin, and the fact that carb consumption causes the secretion of vastly more insulin than the other macronutrients (fats, proteins), carbohydrate consumption is anabolic to muscle tissue. Carbohydrate grows muscle, especially when amino acids from consumed protein are available as well.
What This Means to Athletes
With inadequate levels of carbohydrate, 3 distinct outcomes become more likely:
1) A decrease in single-session motivation and effort due to inadequate blood glucose levels holding back the nervous and muscular system. This means that your workout as early as today could feel the impact of reducing your carb intake. This is especially true for longer duration workouts or higher volume workouts. By the end of the workout you are left feeling gassed and whatever falls at the end of your workout will likely suffer. Furthermore, carb consumption tends to help people perform better on cognitive functions (important for those with jobs that require critical thinking) and can have a positive impact on mood!
2) A decrease in single and multi-session performance due to chronically low muscle glycogen levels. This means that if you are training multiple times a day or if you have many grueling workouts in a week that the workouts later in the week will likely suffer. You won’t have the same energy and motivation to keep up with the demanding workouts. Carb repletion can take up to several days after VERY strenuous workouts or a series of grueling workouts (ex – CrossFit competition spread out over the course of several days).
3) A direct decrease in muscle growth due to decreased hypertrophic signaling from lack of insulin secretion and chronically low muscle glycogen levels. For most strength athletes, the long run idea of having more muscle and having less fat is our best case scenario. By adhering to a low carb diet over extended periods of time you are decreasing the chance you have to grow more muscle. With less muscle, you are less likely to get as strong as you otherwise could. To get even more specific, chronic low levels of glycogen have a direct impact on downregulating mTOR and upregulating AMPk (both are important cellular signaling pathways). Both of these hinder your ability to grow more muscle.
Make no mistake; if you’re a serious strength athlete, low carb diets are not the best way to go. Sure, they can help you lose weight, but the detrimental impact they can and will have on your strength and performance in the gym is very real. There are, of course, some individuals who are exceptions to this rule and ultimately people are drawn to these outliers. For most individuals, they simply cannot withstand the rigors of high level performance on a low carb diet or if they do, their performance will surely not be at an optimal level for the reasons listed above.
Putting It All Together
Despite the appeal of lower carb diets, if you can look past the immediate weight loss results and focus on your long term performance, carbs will be one of your greatest friends in your training. It may seem hard at first to figure out how you can fit more carbs into your diet if you want to lose weight. We can begin to do this by first determining our total calorie balance (calories in vs calories out). Once you have that figured out, you can then go about choosing a starting point for your macronutrient amounts. It’s very likely that you can increase your carb intake while decreasing your fat intake. Fat consumption has quite a bit less of an impact on performance, strength and body composition alterations than protein and carbs. This means that we can lower our fat intake (remember 1g of fat is equal to 9 calories vs just 4 calories per 1g of protein or carbs) to make room for our increased carb intake. So long as the calories are controlled for, raising your carb intake and reducing your fat intake should give you the added energy in your workouts and help you build more muscle in the long run while not adding more total calories into your diet. A final note is to mention that much of this article is focused on training days. There is a time and a place for lower carb days and those days are likely best saved for your rest days. This article is meant to address chronically low carb diets and the impact they will have on your training and recovery.
For serious strength athletes, if you can look past the initial appeal of low carb diets you will likely find that consuming more carbs will make your training feel easier and more productive. You will likely have more energy in and out of the gym, feel better recovered, and should be able to grow more muscle in the long run. These are all huge benefits to athletes everywhere. Don’t let the outliers with exceptional genetics mislead you into thinking that low carb diets are the way to go for strength and performance. There’s a reason LeBron James can get away with a low carb diet: he has some of the best genetics in the world! He could likely eat McDonald’s for all his meals and still be one of the best NBA players of all time. Hopefully, this article will open the eyes of many strength athletes that fall victim to low carb dieting and maybe, just maybe, this is some ammo to fight back in the war on carbs.
- Dialing in Your Diet for YOUR Goals by Dr. Mike Israetel
- The Laws of Optimizing Body Composition by Dr. Mike Israetel
- Adequate carbohydrate feeding preserves muscle during dieting, low carbs cause negative effects:
- Carbohydrate and fat intakes for athletes:
- General guidelines of intake for strength/power and body composition athletes:
- ACSM Position Stand on Nutrition and Athletic Performance: