Eating more carbs gives you more energy to lift heavier and work out longer.
Evidence from Studies
Supporting (2)
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Glycogen supercompensation in skeletal muscle after cycling or running followed by a high carbohydrate intake the following days: a systematic review and meta-analysis
This study shows that eating lots of carbs after a tough workout makes your muscles store more energy (glycogen). Even though the workout in the study was running or cycling, the same thing happens in weightlifting — more glycogen means you can lift heavier or longer, so it supports the claim.
Postexercise protein-carbohydrate and carbohydrate supplements increase muscle glycogen in men and women
This study found that eating carbs after exercise helps muscles store more fuel (glycogen), which is exactly what the claim says happens when you eat more carbs. Even though it didn’t test weightlifting, the science behind it still supports the claim.
Contradicting (2)
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The Effect of Carbohydrate Intake on Strength and Resistance Training Performance: A Systematic Review
The study found that eating more carbs doesn’t usually help people lift heavier or do more reps during strength training, unless they’re really tired or haven’t eaten all day. Most of the time, it made no difference.
The study says eating lots of carbs isn’t needed to get stronger or do more reps during weight training — even with low carbs, people can still perform just as well and build muscle.