Mixed
Combining 3g/day calcium HMB with high protein intake (60g on training days, 30g on non-training days) during 12 weeks of resistance training significantly increases leg fat-free mass compared to protein supplementation alone, though it does not significantly increase whole-body fat-free mass.
If you are doing resistance training and already eating enough protein, adding 3g of Calcium HMB daily (split into 6 doses of 0.5g) can significantly boost your leg muscle growth compared to protein alone. However, do not expect this to change your total body weight or scale readings significantly. The benefit is localized to the legs, likely due to the specific training stimulus and metabolic response in large muscle groups.
gains in leg FFM were higher in WP + HMB vs. WP + PLA (arm FFM: + 6.1% vs. + 9.2%, P = 0.2; leg FFM: + 14.2% vs. + 7.0%, P < 0.01)... Combined protein and HMB supplementation resulted in segmental, but not whole-body increases in FFM compared to protein supplementation alone.
Why this rating
Double-blind, placebo-controlled randomized trial with objective MRI and BIS measurements, though the sample size is small (n=16).
Source
Combined protein and calcium β-hydroxy-β-methylbutyrate induced gains in leg fat free mass: a double-blinded, placebo-controlled study
Alexander Stahn et al. · Journal of the International Society of Sports Nutrition · 2020
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