Why athletes are turning away from carbs, and should you be doing the same?
By K. Aleisha Fetters
REMEMBER THE DAYS when we all wanted to “Be like Mike” and fill up on carb-filled Gatorade between quarters? Well, times change, and now everyone is talking about LeBron James’ low-carb ketosis diet, inspired by his recent Instagram posts.
A metabolic state in which the body uses fat as a source of energy instead of glycogen (the body’s stored form of carbohydrates found in the muscle and liver), ketosis practically guarantees weight loss. And it’s apparent that LeBron James’ 6’8” frame has gotten a lot leaner—and, at least he hopes, meaner, per a recent article in Sports Illustrated.
But how do you get the body to run on fat when nature intended for it to run on carbs? Basically, see how low you can go with your carb intake. When you do, the body’s glycogen eventually runs out, and the body reacts by breaking down fat to produce ketones, carbon fragments which can then be used for energy, explains health and fitness-certified specialist, Jim White, R.D., owner of Jim White Fitness & Nutrition Studios and a spokesperson for the Academy of Nutrition and Dietetics. Most guys have to eat 100 grams or less of carbs per day before their pee sticks (yep, you read that right) read positive for ketosis.
Problem is, ketones are nasty little buggars. They turn the blood acidic and cause horribly bad breath, nausea, and decreased appetite (which some people might see as a pro). Plus, if the body’s ketone levels get too high, they can prove toxic to the kidneys and liver, White says. That’s why it’s so important to complete any ketosis diet with the supervision of a doctor.
"I’ve run on a low-carb diet and it is really miserable," White says. "Does it cause weight loss? Absolutely, you’re going to lose weight on this diet. Anybody can lose weight if they put themselves in starvation state. I don’t see vast improvements in performance. However, losing weight—if you have it to lose—can theoretically improve speed and agility."
What’s more, besides fueling your muscles, ketones can fuel your brain—an organ that’s designed to get 90 percent of its food-fuel from carbs, White says. Enter, brain fog and a really crappy mood.
And last but not least, low-carb diets make dehydration—which is already a major threat to athletes—much more likely. Every gram of glycogen in your body comes with a few grams of water. So, while you will carry less water weight when you’re on a low-carb diet, it’s easier to slip into dehydration mode. And water losses totaling just one percent of your body weight can impair exercise performance, not to mention physiological function, according to research published in the Journal of Athletic Training.
So, no matter how LeBron’s ketosis diet plays out with Cleveland, it may not be something you should try.
White recommends the average gym-going guy get about 55 percent of his calories from carbs. If you’re aggressively trying to lose weight, it won’t hurt to cut that down to about 40 percent, but he doesn’t advise eating less than 125 grams of carbs a day—especially if you’re physically active.
Just make sure the vast majority (if not all) of those grams come from good-for-you sources like fruits, veggies, and whole grains. No matter how many carbs you do or don’t eat, you don’t need any of them to be from soda or candy bars, he says. But you already knew that, right?
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