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.

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Evidence from Studies

Supporting (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

This study looked at what happens to muscle energy stores after one workout, and found that, on average, glycogen drops by about 104 units — exactly what the claim says. So yes, one workout really does use up a lot of muscle fuel.

Contradicting (0)

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No contradicting evidence found

Gold Standard Evidence Needed

According to GRADE and EBM methodology, here is what ideal scientific evidence would look like to definitively prove or disprove this specific claim, ordered from strongest to weakest evidence.

Source Study

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

Score: 50

DOI: 10.14814/phy2.70683

Similar Assertions

Lifting weights once can use up a lot of the sugar stored in your thigh muscles, which your body needs for energy during hard exercise.

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0

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People who don’t lift weights regularly lose more muscle sugar during a workout than those who train regularly—likely because their bodies are less efficient at using energy.

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0

90%

The more sets you do in a weightlifting workout, the more your muscle sugar stores get used up—each extra set burns about 11 more units of energy.

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87%

The longer you lift weights in one session, the more your muscle sugar gets used up—every extra minute burns about 1.3 more units of energy.

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87%

Mixing up heavy and light weights in a workout burns more muscle sugar than sticking to one weight the whole time—likely because you do more total work.

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85%