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Your Muscles Still Run on Glycogen. Even on Zero Carb.
Here's the thing nobody tells you when you go carnivore and keep training hard. Your muscles don't stop using glycogen. They can't. Any effort above roughly 70% of max, a sprint, a heavy set, a scramble in BJJ, pulls from stored muscle glycogen. That's the fuel system, and going zero carb doesn't uninstall it.
So the real question isn't whether you need glycogen. You do. The question is how fast you refill it when zero grams of carbohydrate are coming in the door. The answer is: slower than you're used to, but a lot better than the internet thinks. And once you know the rate, you can build your training week around it.
How Much You're Actually Storing
A trained 180 lb male carries roughly 400 to 500 grams of glycogen total. About 80 to 100 grams sits in the liver. The rest, call it 300 to 400 grams, is parked in skeletal muscle. Each gram binds about 3 grams of water, which is why you drop 5 to 8 lbs in week one on carnivore and think you found magic. You found water.
Here's what surprises people. Research on keto-adapted endurance athletes found their resting muscle glycogen sat close to what high-carb athletes carried. Not identical, but in the same neighborhood. Their bodies were building it from scratch. Zero carb doesn't mean zero glycogen. It means glycogen you manufacture yourself.
The Three Supply Lines
Your liver runs a glucose factory called gluconeogenesis. It pulls from three main raw materials, and each one matters differently depending on what you just did in the gym.
- Lactate. This is the big one for lifters and grapplers. Hard glycolytic work dumps lactate into the blood, the liver grabs it, converts it back to glucose, and ships it out. That loop is called the Cori cycle. Your hard session literally creates the raw material for its own recovery.
- Glycerol. Every triglyceride molecule you burn releases a glycerol backbone. Glycerol converts straight into the gluconeogenesis pathway. In extended fasting states, glycerol can supply something like 20 to 25% of new glucose. Higher fat intake and higher fat oxidation both feed this line.
- Amino acids. Mostly alanine and glutamine. This is why your protein intake isn't just about muscle repair on carnivore. It's substrate for glucose production too.
Total output from that factory runs somewhere around 100 to 150 grams of glucose per day for most people. And here's the important part. That rate is fairly steady. It doesn't spike on demand the way a bowl of rice does.
Why the Refill Takes Longer
The math doesn't lie. A high-carb athlete slamming 1.2 g/kg of carbs per hour post-training refills muscle glycogen at roughly 5 to 7 mmol per kg of wet muscle per hour in that first window. It's fast because the glucose is already made. It just has to get absorbed and stored.
On zero carb, your ceiling is whatever your liver can produce, and it has to split that output between your brain, your red blood cells, and your muscles. Muscle is last in line. So instead of a 24 hour turnaround on a fully depleted session, you're looking at closer to 48 to 72 hours for full replenishment after a truly depleting workout.
Stop treating that as a problem. It's a scheduling input.
The Protocol: Build the Week Around the Rate
I coach this in Whistler with guys who lift four days and roll three nights, and it's the same fix every time. They're not undertrained. They're stacking depleting sessions inside a refill window that can't keep up.
Here's the protocol.
- Cap hard glycolytic sessions at 2 per week. That means heavy compound work above 80% 1RM, hard intervals, or live rolling at full intensity. Two. Space them 72 hours apart. Tuesday and Friday works. Wednesday and Saturday works.
- Fill the other days with aerobic or technical work. Zone 2 cardio, drilling, positional flow rolling, submaximal strength work at 60 to 70%. This burns fat, not glycogen, so it doesn't compete for the refill.
- Protein at 1.6 to 2.2 g per kg bodyweight. For a 180 lb guy that's 130 to 180 grams a day. Roughly 2 lbs of ribeye plus a few eggs. That's not just repair. It's raw material for glucose.
- Don't cut fat on training days. Fat oxidation feeds the glycerol line. Eating 3 lbs of lean chicken breast and calling it carnivore starves the pathway you're depending on.
- Sodium at 5 to 7 grams a day. Around 2 to 3 teaspoons of salt. Glycogen storage needs water, water needs sodium. Undersalt and you'll blame glycogen for what's actually a hydration failure.
The First Four to Six Weeks Are Different
Don't judge any of this in week two. Fat adaptation takes 4 to 6 weeks minimum, and during that stretch your glycolytic capacity genuinely drops. Your top-end suffers. Round four feels like round eight.
This is why it works long term. You're rebuilding the machinery to run mostly on fat, which spares the glycogen you do have for the moments that actually need it. But if you keep testing your max every week during the transition, you'll conclude carnivore killed your performance when what killed it was your programming.
Ride out six weeks at reduced volume. Then reassess with real numbers.
What to Track
Measure it or you're guessing. Log these four things:
- Bar speed on your third working set. If it's slow and grindy compared to your first, you went into the session underfilled.
- Round 4 and 5 performance. First two rounds run on ATP and phosphocreatine. Rounds four and five expose glycogen status.
- Session RPE, 1 to 10, logged within 30 minutes. A session that used to feel like a 7 sitting at a 9 for two weeks straight means the refill isn't keeping pace.
- Morning bodyweight. A drop of 2 to 3 lbs that isn't fat loss is usually glycogen and its bound water leaving.
Two bad weeks in a row on those markers, pull one hard session and add a rest day. Reassess in 14 days. That's the loop. Test, adjust, repeat.
You're not fighting your physiology here. You're just working with a slower supply chain. Build the week around the refill rate and the performance follows.
I'm not a doctor. I've coached people and competed myself, so I know what works. But I'm not your doctor. If you have health issues or take meds, check with someone qualified. Everything here is based on what works in practice and what research supports. Your mileage may vary.