Dietary Supplement. Speciality Supplement. 4x the HMB*. Provides muscle & strength support*. Calcium B-Hydroxy B-Methylbutyrate monohyrdate. Met-Rx® HMB 1000. HMB is a metabolite of leucine, a Branched Chain Amino Acid. May help support strength levels and muscles when used in combination with weight training.* * Per capsule, compared to our previous HMB 250mg formula. Met-Rx® Shaping Every Body: 1-800-55-Met-Rx.