The video explains the role of HMB, a metabolite of leucine, in muscle protein synthesis. HMB indirectly stimulates the Mtorc1 protein complex, crucial for muscle growth, by inhibiting the protein sestrin 2. While naturally occurring HMB is insufficient for significant muscle synthesis, supplementation can enhance this process. The video also highlights the benefits of taking HMB before and after exercise and previews a more detailed exploration of Mtorc1 activation in the next video.

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