In its most basic form, carb cycling (or carbohydrate cycling) is an approach to eating in which you greatly restrict your carbohydrate intake for a set period of days, followed by a brief period of medium to high carbohydrate intake. Then you repeat this cycling process: carbs off for a while, then on briefly, then back off.

Carb Cycling: Carbs 101

Before we go further, let me remind you what a carbohydrate is. It’s one of the three macronutrients in your food, fats and protein being the other two. Your body uses each macronutrient for different reasons. Carbs are primarily used by your body for energy.

Carbohydrates come in essentially two forms: simple carbs (think sugar) and complex carbs (think starches). Simple carbs are real easy for your body to breakdown and use right away for energy. Things like sugars from fruits, juices, sodas, candy, and products with refined ingredients in them.

Complex carbs are carbohydrates that take your body longer to breakdown and therefore, your body uses them more for the long haul. Things like whole grain breads, wild long-grain rice, whole grain pastas, and sweet potatoes. Some products kinda fall in a gray area, like pasta, white rice, and white bread. They provide a little bit of both kinds of energy, but without the nutritional benefits which have been stripped away in refining process.

Again, both kinds of carbs are used for energy, it’s just that some provide short bursts right away (this is why when little kids eat sugary snacks, they quickly start bouncing off the walls) and others last longer and have a little bit of a delayed effect (like runners carbo-loading before a marathon).

Carb Cycling: Are carbs the enemy?

Ever since Atkins, South Beach, and The Zone low-carb diets went mainstream, carbs have been getting a very bad rap. But the truth is they’re our primary source of fuel and therefore provide a very important function for us. The problem is that we don’t often use them correctly. We take in WAY more than we need and have excess “fuel” that gets used to make fat. Our ratios are all wrong. A normal dinner shouldn’t be a salad with croutons, a plate of spaghetti, and two servings of white garlic bread.  What we need is some nice grilled chicken on a cup of spaghetti noodles, covered in sauteed peppers, tomatoes, eggplant, and fresh herbs, served with a bright, colorful salad (sans croutons) and no bread.

Carb Cycling: Why does carb cycling work?

When you’re doing an intense program like P90X, Insanity Asylum, or Max30, you’re using an energy source called glycogen, which is stored in your muscles and liver. When you completely run out of glycogen, you “bonk.” You’ll feel this when you’ve really hit the wall, low blood sugar, shakiness, that sort of thing. You need the carbs to help restore your lost glycogen. But take in too many carbs and you’re encouraging your body to store the fat it has instead of converting it to a usable form of energy.

Enter carb cycling.

When you restrict your carbs, you’re encouraging you body to use its fat for energy. Restrict it for too long and you’ll have a hard time replacing the glycogen you’ve used in your workouts. So your workouts will really suffer- less weight lifted, shorter cardio sessions, tiring more quickly, fewer calories burned. Restrict them for a short period of time (like 3 days or so) however, and your body will start metabolizing your fat for energy.

Then reintroducing carbs for a day will help ensure that your glycogen tank never runs dry.

Rinse and repeat.

Carb Cycling: Carb cycling: off days

As a rule of thumb, try to eliminate all sugars (including fruits), starchy vegetables (potatoes and corn for instance), breads, pastas, cereals, and rices. If you focus on avoiding these six kinds of foods, you’ll avoid a good 80% or more of the culprits. Try to stay off of them for three days, though you may have to play around with that number a little. Three days may be too long if you’re trying to add a lot of muscle (doing a program like Body Beast for example). With programs where you’re trying to tone or to shed fat, you may find you can go four days or so without carbs.

Carb Cycling: On Days

On the days you’re having carbs, feel free to enjoy them, just don’t go crazy, especially on the sugars. For the carbs you are eating, try to focus on high-quality carbs (like sweet potatoes, long-grain or brown rice, whole grain breads, etc) and steer clear of the highly processed ones (like crackers, chips, white breads, etc).

REMEMBER: this is not carbo-loading. You’re not trying to focus on an especially high amount of carbs like a marathoner might. You’re just allowing yourself to have some at every meal.

Finally, the carb cycling on day should be just that, one day. I try to time my carb cycling on a day with my weekly cheat meal and that seems to work quite well. In fact, I did some carb cycling for a good chunk of my time when I got my P90X2 results.

Carb Cycling: Duration

Unlike some eating plans, like the “Fat Shredder” plan in P90X, there’s really not a limit to how long you should do this. With the “Fat Shredder” carbs are restricted for up to six weeks. But with carb cycling, because you’re reintroducing them every third or fourth day, as long as you’re getting results (aka shedding fat) and your workout numbers are improving, you’re golden. Again, you may have to play around with it a little, but generally, three days off and one day on will work for most people.

Carb Cycling: Conclusion

What I have found, along with many other athletes, is that carb cycling is a realistic approach to eating. It gives you the energy you need to get the results you want while not restricting fun food so much that you’re constantly feeling deprived.

If you’re looking for a solution that will address your energy demands, as well as your palates, carb cycling could be the answer.

Start My Coaching!