Even if your muscles are growing inside, your body measurements like arm size or BMI might not change after 8 weeks of weight training.
Evidence from Studies
No evidence studies found yet.
What Would Prove This
Per GRADE and EBM methodology, here is what ideal scientific evidence would look like to definitively prove or disprove this claim, ordered from strongest to weakest.
Determine whether resistance training causes detectable changes in anthropometry vs imaging-based muscle size.
A double-blind RCT with 100 young men (20–35 years), randomized to 8 weeks of resistance training or control, with pre/post measurements of upper arm circumference, chest girth, and ultrasound-derived muscle thickness, with blinded technicians and standardized measurement protocols.
Reveal how well limb girths correlate with actual muscle size in active populations.
A cross-sectional study of 150 male lifters aged 20–35, measuring upper arm and thigh circumference alongside ultrasound-derived muscle thickness, calculating correlation coefficients and Bland-Altman limits of agreement.