Without enough carbs, thyroids get lazy and muscles look flat and become hard to grow. Don't get mad, low-carbers. Just get the facts here.
The battle over whether or not carbs are essential for athletes is still very much alive. There's a strong case to be made that power-based athletes should eat moderate to high amounts of carbohydrate to maximize performance. This includes every team sport athlete, every powerlifter, every bodybuilder, every CrossFitter, and every serious recreational lifter. Here's why.
1 – Maintaining Optimal Thyroid Function
The thyroid gland is a very powerful moderator of energy production, growth, body temperature, heart rate, and more. There are several studies, some dating back to the 1970's, that show impairment of thyroid expression with low-carb dieting.
Since the thyroid gland works in harmony with our central nervous system (CNS), it's in a power-based athlete's best interest to make sure he or she is consuming adequate carbs to prevent any pitfalls. Our CNS drives athletic performance, and without a strong functioning thyroid you're doomed to perform poorly, especially if you're a female prone to potential thyroid disease or ESS (euthyroid sick syndrome).
As examples, consider some of the Paleo diet people who, after adopting the controversial diet, soon exhibit symptoms that are similar to thyroid deficiency. They're tired, their muscles are flat, and they're as cold as cavemen in a blizzard without a mastodon fur cape. T3 drops off the scale. It's not good.
On the other hand, consider the pro-bodybuilders that have bucked the age-old practice of preparing for competition by going low-carb. A few years ago, Branch Warren and Jay Cutler consumed between 750 and 1000 grams of carbs a day in preparation for the Olympia. Both looked full and hard thanks to well-functioning thyroids and carbs in general.
2 – Proper Hydration and Keeping Muscles Looking Full
Dr. Edmund Burke discusses in his book the value of ingesting enough carbs after an intense training session to help offset inevitable fluid depletion and electrolyte losses. Burke writes:
"Research has shown that carbohydrate and sodium work together to increase water absorption in the intestinal wall. Carbohydrate's component glucose molecules stimulate sodium absorption, and sodium, in turn, is necessary for glucose absorption. When these two substances are absorbed by the intestines, they tend to pull water with them, thus facilitating the absorption of water from the intestines into the bloodstream."
Moreover, carbs are inherently hydrophilic, or water loving, and a lack of them affects different pathways in the human body responsible for regulating our hydration levels. For example, for each gram of glycogen (stored glucose) in our muscle and liver tissue, we store approximately three grams of water. Muscle and liver glycogen stores are pretty substantial so you could see how this could affect water balance. Want to look totally flat as if you've never worked out a day in your life? Cut out carbs and flush out all that stored water.
Also, when we deplete carbohydrates, there's a concurrent decrease in insulin production that can cause the kidneys to excrete more water. Lastly, if you cut carb intake down low enough to induce ketosis, you create a natural diuretic effect, and a decrease in hydration of just 2-3% can impair athletic performance.
3 – Insulin Production
When you ingest carbs, your pancreas secretes insulin. Moronically, insulin sometimes still gets flack for its role in energy storage, specifically, fat storage. But insulin is powerfully anabolic, too, as it ferries nutrients (including protein) to muscles. No carbs, very little insulin. No insulin, very little muscle.
Additionally, insulin interferes with cortisol's inhibition of leucine, an amino acid that plays a powerful role in muscle protein synthesis. Moreover, insulin activates and influences several key pathways involved in muscle growth, including the mTOR pathway, which pretty much determines how big your muscles can grow.
4 – Avoiding Gluconeogenesis
This metabolic process involves the production of glucose from non-carbohydrate sources. This process can occur from a number of substrates, but let's focus on gluconeogenesis as it relates to specific amino acids. If your carb intake is low, you force your body to produce sugar from amino acids (among other things), which could result in muscle loss and declines in performance, especially if high-intensity activity is being performed on a regular basis.
Of course, gluconeogenesis and the loss of muscle doesn't much matter for obese individuals or endurance athletes, as low-carb diets have a minimal impact on them. However, this doesn't apply to muscular and explosive team sport athletes who need a steady flow of carbohydrates to maintain an awesome physique and superlative performance. It also doesn't apply to those WANTING to get muscular and explosive.
5 – Maintaining Healthy Levels of Vitamins and Minerals
When you avoid an entire category of macronutrients (carbs), as many anti-carb people are wont to do, you deprive your body of a tremendous treasure chest of micronutrients. 'Nuff said.