Carb Back-Loading: Training Without Carbs

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By John Kiefer

I didn’t get into the nutrition field under the most pleasant of circumstances. Like a lot of people in the fitness industry, I started researching nutrition and training out of necessity. Being a scientist by trade—I’m trained as a physicist—allowed me to cut through scads of BS to find studies and information that actually applied to what I, and many others, needed. In terms of what motivated me to start searching in the first place, however, there’s a very simple and unpleasant explanation: I was an overgrown fat kid.

A few years back, after a software job had me tethered to my desk all day and night, my body was almost completely debilitated as a result of a lack of proper training and a terrible diet. I hadn’t yet discovered the magic of Carb Back-Loading™, so I tried to work myself back into shape by doing what I knew: a combination of Carb Nite® (my super-low-carb diet program) and a six-day-per-week training split.

Gaining strength wasn’t a factor for me at this point. I only cared about how I looked, which explains my virtually zero-carb mindset at the time. As a result of this system I’d cobbled together, I managed to lean down from a flabby 240 pounds to a fairly ripped 204, and I did it quickly. Since I was carrying extra fat—and since I’ve always been strong and wasn’t starting from scratch in terms of muscle memory—I managed to regain some mass, while losing fat at the same time.


Something else happened, though—something that came as a big surprise to me. My gym strength started increasing at a rapid clip. I’m differentiating between “gym strength” and “real-world strength” here, because outside the gym, the lack of carbs had me feeling depleted and weak. In the gym, however, once I was lying on a bench under a barbell, something miraculous took place. I’d do the first few reps of my warm-up sets, and then, when I stood back up afterward, I’d be shaking as though I’d just mainlined a vial of straight caffeine. After that, I’d be extremely strong for the remainder of the workout.

This wasn’t just an energy level thing. My numbers kept rising in every lift—especially my bench press. When I first got back in the gym, I was having trouble with 225 pounds, but after a very short period of time, I nailed 405 at a bodyweight of 202. I still felt awful outside the gym, but I was astonished at what I call this Hulk Effect going on every time I wrapped my hands around a barbell.

In the last installment of this serious, I explained the scientific process of observation, explanation and experimentation. Scientists see things, try to explain them, then attempt to validate their explanations through experimentation. Well, I was making one heck of an observation here. I was inexplicably feeling a lot stronger in the gym for no apparent reason I could think of. As a scientist, I needed to know what was causing this.


First off, let’s define low-carb for the purposes of this discussion. When I talk about a low-carb diet, I’m specifically referring to days where you’re taking in 30 grams or less of usable carbohydrates. By usable, I’m not including fiber, since fiber can only provide energy once it ferments into short-chain fatty acids in the colon[1,2]. Fiber is a carbohydrate, but it provides energy as a fat. Research has shown that the effects attributed to ketogenic diets occur at this 30 gram or less level for nearly everyone. Over 30 grams, however, and it turns into something of a crapshoot[3-18].

Now, when you’re going on 30 grams of carbs or less each day, you’re going to exhaust your glucose reserves in a day or two. Once this happens, you’ll be training with depleted glycogen stores. Fat can pick up the slack at this point, at least for the energy requirements necessary for strength—although you’ll likely have trouble maintaining a high training volume. Empty glycogen stores seem to have no bearing on the stimulation of muscle growth through resistance training[23], and may actually accelerate fat loss[24,25]. What this condition can change, however, are the mechanics of your lifts and your rate of recovery—so bear in mind that your gym performance may not actually correlate to your maximum lifting numbers.  


Where does this whole Hulk Effect thing come from, then? Well, it’s produced by a combination of enhancements to your central nervous system and sympathetic nervous system—enhancements that may, in fact, result from the absence of carbs.

Stripping carbs from your diet appears to make the central nervous system function with greater efficiency—as motor signals increase in amplitude[26]. This allows for an increase in single-rep power production and fine-motor control[27] (referred to in scientific literature as psychomotor performance). In other words, your ability to coordinate movement is augmented by the absence of carbs.

I instinctively knew this to be the case, so I wasn’t surprised. When you load up on carbs throughout the day, you’re maintaining your blood sugar levels by external means—and your body has to deal with it in order to maintain homeostasis. Because neurons contain droves of GLUT3 transporters that vacuum up glucose at will[28], your cell function and efficiency is sensitive to swings in your blood sugar level.

Letting your body control its own production and management of blood sugar, in contrast, allows your nervous system to remain fine-tuned and prepared to perform. Your blood sugar content at any given time is only four grams[29], so this isn’t as difficult to maintain without carbs as you might think. It’s also an amount your body can supplement with ketones—a high-efficiency fuel for nerve tissue[30].

Still, this doesn’t fully explain the Hulk-like transformation I experienced at the beginning of each workout after performing my first warm-up set or two. That’s where the sympathetic nervous system enters the equation. Your sympathetic nervous system controls catecholamine response, and the best-known catecholamine is adrenaline. When you train, your body releases catecholamines. This, in turn, increases fatty acid release, energy production, and strength. Your muscle system’s response depends on how much adrenaline is present, its rate of release, and how sensitive your cells are to it. Stripping carbs from your diet does something to intensify each of these[31-36].

When you go low-carb, your adrenal glands release catecholamines with less stimulus or stress. This explains why I was so jacked up with adrenaline after my light-to-moderate warm-up sets. All it took was a few reps, and this mechanism would begin to fire like nobody’s business. With a low-carb diet, this flow of adrenaline starts sooner, and your body dumps larger quantities—kind of like ramming a six-inch needle into your chest and injecting it at the start of your workouts.

Your cells are very sensitive to this adrenaline that’s entering your system. Sending your body into ketogenesis increases your cellular response to catecholamines, and the whole package gives you a serious fight-or-flight response. As a result, you’ll get power, strength, irritability, and enough rage to fuel some majorly ass-kicking workouts. By living this low-carb lifestyle, you’ll be able to summon this Hulk Effect anytime you want—and not just when you’re angry.

Following Carb Back-Loading entails eating fat to burn fat, and training each day without having eaten carbs prior to your workouts. Limiting carbs in the first half of the day forces your metabolism to rely on fat for its energy needs. When you limit your intake of food during this time, your body releases body fat for energy. That’s how Carb Back-Loading works.

What matters when you train are your glycogen stores, and not the carbs you ingest. I’ll cover all-things-glycogen related in the next installment of this series. For now, however, I’ll let you off with a warning. Eating carbs immediately before you train can cause poor performance and potentially rebound hypoglycemia, which happens when muscles, the liver, and other tissues clear glucose from your bloodstream too fast. This manifests itself in the form of shakiness, sweating, light-headedness, and an inability to think clearly. You don’t want to get under a heavy barbell in this condition, believe me.


Now, if you’re a serious strength athlete—a powerlifter or strongman, for example—you likely don’t want to switch over to a completely low-carb life. It’s not the most enjoyable way to live, and you’ll have to modify your training because you’ll lack the endurance to handle the type of volume you need. What I’ve found, however, is that when you transition from a low-carb diet back to a normal one, this Hulk Effect can linger for up to a month—although I have no research to back this up yet. This also holds true for Carb Back-Loading. When used correctly, Carb Back-Loading can help you summon The Hulk Effect for months.

Give it a shot. At least on a temporary basis, you’ll enjoy the hell out of channeling your inner weight-smashing, PR-destroying self.

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DH Kiefer is a Physicist turned nutrition and performance scientist. He’s been researching, testing and verifying what hard science proves as fact for over two decades and applied the results to record-holding power lifters, top ranking aesthetic athletes, MMA fighters and even fortune 500 CEOs. He’s the author of two dietary manuals, The Carb Nite® Solution and Carb Back-Loading™, and the free exercise manual Shockwave Protocol™. He’s currently considered one of the industry’s leading experts on human metabolism and plans to stay there. He’s a featured writer in every issue of FLEX and Power Magazine. You can learn more about him at www.dangerouslyhardcore.com

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