Strength Training and Glycogen: Understanding the Real Energy Consumed

# Heavier Doesn’t Mean More Glycogen: What Strength Training Really Consumes

**by Laurent Glatz – for Athletic Carnivore**

A common belief still echoes in gyms: the heavier the session, the more energy it consumes, the more glycogen stores it depletes, and therefore the more carbohydrates you need to load.

This reasoning seems obvious.

Yet, it’s far too simplistic.

A meta-analysis published at the end of 2025 in *Physiological Reports*, analyzing 20 studies with 180 participants, offers a particularly insightful finding: during resistance training, muscle glycogen depletion increases primarily with **the number of sets and the session duration**. Conversely, it tends to decrease as intensity expressed as a percentage of 1RM increases.

In other words: lifting very heavy weights does not automatically mean consuming more glycogen.

And this nuance changes a lot.

A powerlifter performing a few very heavy repetitions with long rest periods and a bodybuilder chaining twenty sets of eight to fifteen reps do not demand the same thing from their bodies, even if the former handles much heavier loads.

So the question isn’t just: **how much do you lift?**

The real question is: **what metabolic work are you actually imposing on your muscle?**

Muscle Doesn’t Rely on a Single Fuel

Muscle contraction requires ATP. But the body has several ways to regenerate this ATP.

During an extremely short and explosive effort, like a heavy repetition or a near-maximal lift, a significant portion of immediate energy comes from the phosphagen system, notably phosphocreatine.

This system can deliver a huge amount of energy very quickly.

Its drawback is that it depletes rapidly.

However, when you take several minutes between sets, a large part of this phosphocreatine can be restored before the next effort.

Thus, the metabolic profile of a heavy training session with few reps and long rests becomes very different from that of a session where sets lengthen, repetitions accumulate, and rest periods shorten.

In this second scenario, glycolysis plays a larger role.

And glycolysis notably uses muscle glycogen.

Here lies the classic mistake.

People often confuse **mechanical intensity** with **glycolytic cost**.

Lifting 200 kg once is mechanically extremely demanding.

But performing ten, fifteen, or twenty sets with prolonged time under tension can represent a much greater demand on local glycogen stores.

The meta-analysis precisely confirms this logic: more sets and longer sessions were associated with greater depletion. The authors estimate that a resistance training session reduces muscle glycogen by about 21% on average, with significant variations depending on protocols.

And these variations are precisely the most interesting point.

Bodybuilding and Powerlifting Pose Different Nutritional Questions

Let’s consider two athletes.

The first focuses on maximal strength. He performs low repetitions, uses heavy loads, and rests several minutes between sets.

The second aims more for hypertrophy with high volume, multiple exercises per muscle group, more repetitions, and much longer time under tension.

Both do strength training.

But biologically, their sessions tell very different stories.

The second accumulates more contractions, more total work, and often more glycolytic demand.

That’s why talking about “carbohydrate needs for strength trainees” as if there were a single category of athlete doesn’t make much sense.

Training type matters.

Duration matters.

Volume matters.

Frequency matters.

Adaptation level matters too.

In this meta-analysis, trained subjects actually showed slightly less glycogen depletion than untrained ones. The authors suggest better metabolic and neuromuscular efficiency as possible explanations, while emphasizing that these mechanisms still require further study.

This is exactly where generic advice starts to become misleading.

Two people can follow the same low-carb diet.

Two people can eat the same amount of carbohydrates.

Two people can train strength five times a week.

Yet their actual glycogen needs can be very different simply because their sessions are nothing alike.

Low Carb, Keto, Carnivore: The Question Isn’t “Is It Compatible with Strength Training?”

That question is too crude.

An athlete doing three heavy lifts, a few short sets, and taking long rests probably doesn’t have the same glycolytic pressure as a bodybuilder performing twenty sets close to failure.

That doesn’t mean glycogen becomes useless for the first.

Nor does it mean a low-carb or carnivore diet automatically guarantees perfect performance.

It simply means you can’t deduce an athlete’s nutritional needs from the single word “strength training.”

This is especially important for those on carnivore, low-carb, or ketogenic diets.

Some maintain excellent maximal strength.

Others feel a drop mainly when volume increases.

Others perform well during early sets but see their performance collapse in later ones.

This isn’t necessarily contradictory.

It may simply reflect different energy demands.

And this is where it becomes easy to correct the wrong parameter.

An athlete lacking recovery might think they lack carbohydrates.

Another might increase carbs massively even though their training mainly relies on maximal strength and low volume.

A third might stay extremely low-carb while doing very glycolytic sessions and then conclude their diet “doesn’t work.”

In each case, the problem isn’t necessarily the chosen diet.

The problem may be a misreading of the real metabolic demand of the training.

Average Glycogen Levels Might Not Tell the Whole Story

Another important nuance: most studies measure total muscle glycogen.

But glycogen stores aren’t distributed like a simple homogeneous reservoir.

Some fractions located near contractile structures might play a particularly important role in muscle function.

The authors therefore highlight that a relatively modest average depletion doesn’t necessarily reveal exactly what’s happening in certain muscle compartments.

This is another reason to avoid statements like:

“Strength training uses X grams of glycogen.”

This single figure practically doesn’t exist in real life.

It all depends on what you do with the barbell.

And especially on how your body responds to that work.

The Real Problem: Copying a Strategy That Fits Another Athlete

The bodybuilder sometimes copies the powerlifter’s diet.

The powerlifter copies the runner’s.

The carnivore athlete copies an athlete who’s trained in ketosis for ten years.

And each ends up drawing general conclusions from a context that isn’t theirs.

This is exactly how you can waste weeks tweaking the wrong parameters.

Adding carbs when the problem is sleep.

Cutting carbs further when training volume has become huge.

Blaming ketosis when recovery is insufficient.

Or quitting a working diet simply because you copied a training program whose energy cost no longer matches your current adaptation.

So the real question isn’t whether carbs are “good” or “bad” for strength training.

The real question is to know **how much your training truly depends on glycolysis, how you recover between sessions, and how your own physiology responds to this demand**.

At this point, reading one more nutrition tip isn’t necessarily enough.

You need to connect effort type, volume, recovery, diet, metabolic history, and real performance sensations.

This is precisely where personalized analysis becomes useful: not to impose a diet, but to understand what truly fits your physiology.

**Is your lack of energy really due to a carbohydrate deficiency… or have you simply never analyzed the real metabolic cost of your training?**

**Understanding My Metabolic Terrain**

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