Like intermittent fasting, the carb cycling diet has some pretty big shoes to fill if you listen to its more fervent advocates.
According to them, carb cycling delivers the holy grail of bodybuilding: rapid fat loss while preserving, or even building, muscle. The more ridiculous claims go even further, enticing you with promises that you won’t have to count calories, and the allure of the high-carb day, wherein you stuff yourself silly with precious carbohydrates.
Another common selling point of the carb cycling diet is the claim that a traditional approach to dieting (steady protein, carbohydrate, and fat intake throughout the week, with planned cheats/refeeds) simply can’t get you to the “super lean” category (6% and under for men, 16% and under for women) without burning up a ton of muscle.
Well, in this article we’ll not only dive into what carb cycling is and how you do it, but we’ll also cut through the hype and hyperbole surrounding the matter and use a bit of science and anecdotal experience to get at its heart.
The carb cycling diet is very simple. It works like this:
Exact protocols vary in terms of specific numbers, but all are based on that simple structure. For example, you may do 4 low-carb days, followed by a high-carb day, and then a no-carb day, and then start over. Or you may do 3 low-carb days followed by 1 high-carb day, and then back to the low-carb and so on.
Here’s what these days often look like numerically:
The theory behind the diet is as follows:
Your high-carb day will refuel your muscles’ glycogen levels and flood your body with insulin, which has anti-catabolic effects (but not true anabolic effects like some people claim–insulin does not induce protein synthesis, but rather inhibits muscle breakdown). Most protocols recommend that you do your toughest workout on your high-carb day.
Your moderate-carb day gives you plenty of carbs to maintain glycogen stores, but doesn’t put you in enough of a caloric deficit to cause much weight loss. You train on these days.
Your no- and low-carb days are the days where you’re in a caloric deficit, and where some people claim the “magic” happens. These are the days where you “trick” your body into burning fat at an accelerated rate by keeping insulin levels low. It’s usually recommend that you use cardio or rest days for now/low-carb days, but if you lift more than 3 days per week, you will have to lift on 1 or more of these days. (Which sucks–more on this later.)
So, that’s how to do it. Let’s address the next question on your mind: does it work?
Can you use carb cycling to lose fat? Absolutely.
Any dietary protocol that puts you in a caloric deficit, whether it’s daily or weekly or even monthly, will result in weight loss, regardless of the macronutrient breakdown.
Let me state this again:
So long as you keep yourself in a caloric deficit–meaning you give your body less energy than it expends–you will lose weight, regardless of whether the energy comes from protein, carbohydrate, or fat.
Part of the appeal of carb cycling are the claims that you don’t have to “count calories” or really “watch what you eat.” You simply follow a set of simple rules regarding eating “a lot” of carbs on high days, less on moderate days, and very few on no/low days.
This loose style of dieting works decently for maintenance, and may work for weight loss to a degree, but never works for getting shredded.
Getting below 8-9% body fat (men) or 18-19% (women) requires that you plan and track your macronutrient intake closely. Period. You need to know exactly how much protein, carbohydrate, and fat you’re eating every day, and you need to manipulate these numbers to keep yourself in enough of a caloric deficit to continue losing fat, but not so much that you sacrifice muscle.
So the question of carb cycling and weight loss becomes…
Enthusiasts of the carb cycling diet will claim that your low-carb days will greatly accelerate your fat loss over what it would be with a traditional approach to dieting.
Unfortunately, science isn’t on their side.
Let’s start with a study conducted by the University of Pennsylvania, which had 63 obese adults follow one of two diets:
The result: the low-carbohydrate group lost more weight in the first 3 months, but the difference at 12 months wasn’t significant.
The 3-month result isn’t surprising, considering the fact that reducing carbohydrate intake reduces water retention, and also decreases the amount of glycogen we store in our liver and muscles, which further decreases total body water retention. This, of course, causes a rapid drop in weight that has nothing to do with burning fat (and anyone that has reduced carbohydrate intake as a means of cutting calories for weight loss has experienced this).
Next is a study conducted by Harvard University on diet composition and weight loss. Researchers randomly assigned 811 overweight adults to one of four diets:
The result: after 6 months, participants assigned to each diet had lost an average of 6 kg, began to regain weight after 12 months, and by 2 years, all had lost an average of 4 kg. Researchers concluded the study with the following (emphasis added):
“Reduced-calorie diets result in clinically meaningful weight loss regardless of which macronutrients they emphasize.”
A study published by Arizona State University found that an 8-week high-carbohydrate, low-fat, low-protein diet was equally effective in terms of weight loss as a low-carbohydrate, low-fat, high-protein diet.
Particularly relevant to this post is another study conducted by Arizona State University, wherein researchers pitted a ketogenic diet (a very low-carbohydrate diet) versus a traditional diet to see if one had a metabolic advantage over the other.
In this study, 20 overweight adults were randomly assigned to one of two diets:
After 6 weeks, the results were as follows:
So, what you should take away from this section of the article is that the theory that low-carb days deliver the big fat loss punch of carb cycling are not supported by literature. They are simply part of the marketing pitch.
Before we move on, however, I’d like to mention that there is a scientifically supported exception to the above statement. That is, there are cases where some people do lose more fat by reducing carbohydrate intake (and the flip side is true as well–some people lose more fat by increasing carbohydrate intake).
How does that work and why? Check out my article on carbohydrates and weight loss to learn more about it.
For the purposes of this article, however, just know that some people’s bodies have problems digesting and using carbohydrates properly. This is due to impairments in insulin production and processing. For those people, reducing carbohydrate intake can help with weight loss. In my experience, however, this isn’t very common, and problems with insulin production and sensitivity can be vastly improved with diet and exercise.
I both advocate and use a traditional approach to dieting because it’s simple, and it works very well when you do it right. The best diet is the one you can stick to, and you can get as lean as you want with traditional dieting.
Don’t believe me?
Well, I just finished an 8/9-week cut using a traditional diet (40% of calories from protein, 40% from carbohydrate, and 20% from fat).
I lost about 13 pounds and went from ~9% to ~6%, and my strength increased for the first 4-5 weeks, and then decreased back to my pre-diet numbers over the course of the last several weeks (and this was simply because I had to gradually reduce my calories, and I chose to pull from carbs–this makes workouts harder).
Here are a couple pictures of how I currently look:
You can’t get shredded eating 150-200 grams of carbohydrate every day? Please tell me more. Mr. Carb Cycler…
Okay then, let’s steam forward to the next big, bold claim made to sell people on carb cycling…
The short answer?
But it’s not the carb cycling per se that would make this possible. It would be your current level of conditioning, your training history, and your genetics.
For instance, I email with scores of guys and gals every day that are losing fat and building muscle on my Bigger Leaner Stronger and Thinner Leaner Stronger programs, but they usually fit a certain profile:
Under those circumstances, I actually expect people to both lose fat and build muscle while following my programs. But I don’t try to claim it’s because of the magical quantum mechanics of my methods like some carb cycling hucksters. It’s simply because the body responds incredibly well to proper diet and training, and especially in the beginning. Newbie gains are real, and are a lot of fun.
But if you’re an advanced lifter that is approaching your genetic potential, I can guarantee you that you will not build muscle while losing fat without steroids, regardless of what you do in the kitchen or gym. What you can strive for, however, is maintaining the muscle you have by never putting yourself into too deep of a deficit, and not going overboard with too much steady-state cardio.
Another aspect of this “metabolic advantage” claim for carb cycling is that your high-carb day will give your body an “anabolic, muscle building boost” while simultaneously “shocking” your metabolism into high-gear, thus accelerating fat loss.
As you probably expect by now, these claims just aren’t supported by science.
I mentioned earlier that insulin can help preserve lean mass, but does not induce muscle growth, and any metabolic boost that comes with increased caloric intake is offset by the extra calories themselves. That is, you can speed your metabolism up by eating more, but never to a point where you’re burning the extra calories consumed plus additional fat.
Also relevant to this claim in the fact that most people basically feel like shit on their no/low-carb days. If you want to know what carb cravings are really like, eat less than 50 grams of carbs per day for a week.
Training on a no/low-carb diet is even worse, and 1-2 higher carb days is not enough to offset this. If you want to drag ass and have basically the worst workouts ever, try to lift with any intensity on a no/low-carb day. Furthermore, a big part of maintaining lean mass while cutting is continuing to lift heavy weights and maintaining your strength, and drastic reductions in carbs make this impossible.
The bigger issue here is what Martin Berkhan called “fuckarounditis.” If we want to be more politically correct, we can call it “shiny object syndrome.”
That is, too many people are looking for magic bullets, quick fixes, advanced body hacks, and other nonsense to reach their goals. One week they’re following the Rebel Max Anabolic Anaconda Program, the next the X-Physique Metabolic Recomposition Program, and on, and on.
I have sympathy, but they’re basically the hipsters of the lifting community. They’re drawn to whatever is trending, whatever’s buzzworthy. And they’re always stuck in a rut.
I get emailed every day by people afflicted with fuckarounditis. It usually goes something like this:
“I’m currently following an intermittent fasting protocol combined with some carb cycling and backloading. In the gym I’m training twice per day on a power/hypertrophy triple-split, and I’m periodizing with volume training. Why am I not big and lean like you? What type of cutting-edge protocols do you follow?”
My reply usually leaves them a little baffled. I share my secrets:
That’s it. That’s all it takes.
Resist the allure of shiny objects. Don’t contract fuckarounditis.
I’ll make this section short and sweet:
If you know your body doesn’t do well with carbohydrates, then carb cycling may help you lose weight. Otherwise, don’t bother with it. It doesn’t deliver on its exaggerated claims, and training and, well, living on a no/l0w-carb diet sucks.
If you liked this article, then you’ll love this book…
Many people claim that eating right is more important than training right when it comes to building muscle and losing fat…and they’re wrong. It takes BOTH proper nutrition and proper training to transform your body.
The truth is if you know how to train, eat, and rest properly, then you can build muscle and lose fat every week…and actually see the changes in the mirror.
And that’s why I wrote Bigger Leaner Stronger for men, and Thinner Leaner Stronger for women: they lay out EVERYTHING you need to know about diet and training to build muscle and lose fat effectively…
I’m Mike Matthews and I’ve been training for nearly a decade now. I believe that every person can achieve the body of his or her dreams, and I work hard to give everyone that chance by providing workable, proven advice grounded in science, not a desire to sell phony magazines, workout products, or supplements. More about me.