Whether you use light or heavy weights, your muscles can grow about the same amount if you train hard enough—both methods work for building muscle size.

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Against

Evidence from Studies

Supporting (1)

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Divergent Strength Gains but Similar Hypertrophy After Low-Load and High-Load Resistance Exercise Training in Trained Individuals: Many Roads Lead to Rome.

Randomized Controlled Trial

Human

2025 Sep 1

This study found that lifting light weights for many reps and lifting heavy weights for few reps both made people’s thighs about the same size after 9 weeks — so neither method is clearly better for building muscle size.

Contradicting (0)

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No contradicting evidence found

Source Study

Divergent Strength Gains but Similar Hypertrophy After Low-Load and High-Load Resistance Exercise Training in Trained Individuals: Many Roads Lead to Rome.

Score: 25

DOI: 10.1152/japplphysiol.00353.2025

Similar Assertions

The lower part of your thigh doesn't get noticeably thicker no matter which kind of weight training you do, if you're already trained and train for 8 weeks.

85%

After 8 weeks of any kind of weight training, the lower part of the thigh doesn’t get noticeably thicker—even though the upper and middle parts do.

85%

No matter which way you train—rest-pause, drop sets, or regular sets—if you do the same total amount of work for 8 weeks, your upper and middle thighs grow about the same.

84%

If you lift weights twice a week for 8 weeks and do the same total amount of work, your upper and middle thighs will get thicker — no matter what fancy technique you use.

83%

The lower part of the thigh doesn't get noticeably bigger after 8 weeks of any of these training styles, even if the upper and middle parts do—meaning muscles don't grow evenly everywhere.

83%