Ketogenic Diet 101 provides an overview of the ketogenic diet and discusses how cutting carbs can affect athletes.

Ketogenic Diet

If you're an athlete training hard and working out regularly, carbs are an extremely important part of your diet—they're the fuel that keeps you going in overtime.

The unfortunate truth, however, is that most athletes eventually turn into desk jockeys. Sure, they hit the gym a few days each week, but those extra carbs they used to burn when coach had them running wind sprints after practice now pile up around their midsections.

One option for fast weight loss: the Ketogenic diet. At its core, the idea is to cut carbohydrates to a negligible level, forcing your body to run on a different source of fuel, namely, your body fat. The diet does slash fat, but not without drawbacks.

How Does A Ketogenic Diet Work?

Your body uses carbohydrates in a few different ways. It can burn the energy as glucose immediately, it can store it as glycogen for future use, or it can store it as fat. Think of your glucose and glycogen stores as tanks that can be filled up. Once both of them are capped off, the remaining energy spills over and lands on your waistline as flab. Obviously, you don't want that.

If you severely cut down on carbs, however, your body adapts by running on the very thing you're trying to keep in check: fat. The process is called ketosis.

Remember those fuel tanks? Okay, now imagine tapping both of them out. Your body is completely devoid of carbohydrate energy. After a few days with a very low amount of its preferred fuel, your body turns to fat to power your engines. The fat is converted to fatty acids and ketone bodies for fuel—hence the name.

But unlike carbs, your body doesn't store unused ketones as fat.  Instead, your body sucks away the fat you have (as well as the fats you're ingesting) to keep you going, and whatever isn't used is simply discarded—so what's not to love?

Here's the Catch

When something seems too good to be true, it's usually for good reason.  While on the surface the ketogenic diet might seem like a killer option for dropping flab and keeping it off, it's probably not the best way for athletically inclined individuals.

"Ketogenic diets are something that I hate," says Nate Miyaki, certified specialist in sports nutrition and author of The Samurai Diet: The Science and Strategy of Winning the Fat Loss War. "They're sold as a way to maximize fat loss. But I don't think they're necessary."

"There are a lot of metabolic and hormonal drawbacks to the ketogenic diet, especially when combined with anaerobic training," says Miyaki. "[Keto with anaerobic training is becoming] very popular in CrossFit circles. I work with a ton of people who come to me and say that 'my hormonal profile is shot, I have no testosterone, my thyroid is shot, my metabolism is gone, I'm skinny fat despite a large calorie deficit and no carbs.'"

On top of all that, research suggests that a ketogenic diet may increase your chances of developing painful kidney stones.

"The keto diet hooks people because it shows results on the scale," Miyaki says. "But you lose a lot of water weight and lean muscle mass along with your fat."

A Better (And Easier) Way

"There is no need to go full blown keto [to lose fat]," says Miyaki. "You can do some things with carbs and their timing to optimize fat loss without having to go into a ketogenic state where you have some of those drawbacks."

Miyaki suggests following a near Paleo diet during the day—no starchy stuff or sugars. Instead, snack on nuts and veggies for some incidental carbohydrate energy.

Miyaki suggest tying the majority of your carbs to your workout, before and after. Before your workout, down a piece or two of fruit for some quick energy, then post-workout, ingest some clean carbs like white rice, potatoes, or sweet potatoes to refill lost muscle glycogen.

The Bottom Line

Although a ketogenic diet can cut fat and offer you the athletic physique you're chasing, its many the drawbacks outweigh its benefits.

If all of this is confusing, Miyaki recommends thinking about your body as a car engine, and carbs as your gas. "If your car is sitting in the garage all week you don't go gas it up," he says. "It's the same with your diet. If you're an athlete or active, well that's like driving. If you drive your car around, you fill it up; if you work out, you eat some carbs."

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