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v1
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quantitative
Analysis v1
Contested

Even a hard weightlifting session only uses up about 40% of your muscle sugar stores.

37
Pro
50
Against

Evidence from Studies

Supporting (2)

37

Community contributions welcome

37

Glycogen resynthesis in skeletal muscle following resistive exercise.

Randomized Controlled Trial
Human
1993 Mar

This study had people do a tough leg workout and found their muscles lost about 40-44% of their stored energy (glycogen), which is right around the 40% maximum the claim says happens — so it supports the claim.

20

The Effect of Carbohydrate Intake on Strength and Resistance Training Performance: A Systematic Review

Systematic Review
Human
2022 Feb 18

The study didn’t measure glycogen directly, but it found that even when people did lots of weightlifting, they only needed carbs to perform better if they were really tired or hadn’t eaten — meaning their muscles probably didn’t run out of fuel completely.

Contradicting (1)

50

Community contributions welcome

50

Acute effects of resistance exercise on skeletal muscle glycogen depletion: A systematic review and meta‐analysis

Systematic Review With Meta-Analysis
Human
2025 Dec

The study found that a single workout can drain way more than 40% of your muscle energy stores — sometimes over 70% — especially if you do lots of sets, which goes against the claim that it never goes above 40%.

Similar Assertions

Glycogen depletion during resistance training is negligible in non-fasted individuals performing ≤10 sets per muscle group per session.

20
50
91%

Even after a really tough weightlifting session, your muscles don’t run out of fuel fast enough to slow you down, and they can refill just fine even if you don’t eat carbs for a while.

20
0
88%

People who don’t lift weights regularly burn more sugar from their muscles during a workout than people who lift regularly.

50
0
84%

Changing the weight you lift during a workout burns more muscle sugar than lifting the same weight the whole time.

50
0
83%

After a weightlifting workout, the main leg muscle loses a lot of its stored sugar energy—about 21% on average—which can make you feel tired and affect how well you do in your next workout.

50
0
83%

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