Long-term Effects of Calcium beta-Hydroxy-beta-Methylbutyrate and Vitamin D3 Supplementation on Muscular Function in Older Adults With and Without Resistance Training: A Randomized, Double-blind, Controlled Study.

In this year-long study of 117 older adults (≥60 y) were studies in four treatment arms: 1) 3 g HMB plus 2,000 IU Vitamin D per day with exercise; 2) 3 g HMB plus 2,000 IU Vitamin D per day with no exercise; 3) Placebo with exercise; and 4) Placebo with no exercise.  All participants had baseline Vitamin D levels from 15-30 ng/mL, which would be considered insufficient for optimal physical functioning.  HMB plus Vitamin D supplementation significantly increased lean mass within the non-exercising group at 6 months.  Additionally, in the non-exercising groups knee extension peak torque (60⁰/s) was significantly improved at 3 months in the HMB plus Vitamin D group compared with the non-exercising placebo group.  A functional index of the physical tests, which included handgrip strength, get up, and get up and go measurements, showed that HMB plus Vitamin D resulted in a significant increase in the functional index at 3, 6, and 12 months of the study.  The authors concluded that HMB plus Vitamin D could enhance muscle strength and physical function in older adults even without engaging in an exercise program.



Time-restricted feeding plus resistance training in active females: a randomized trial.

The effects of HMB supplementation during 8 weeks of time-restricted feeding were studied in young, resistance-trained women. Time-restricted feeding is a type of intermittent fasting, where all daily calories are consumed during a smaller “feeding window” each day. Each study participant was assigned to either time-restricted feeding (TRF, 8 hours) or the control group (no feeding time restrictions). Half of the women in the TRF group took three 1g doses of HMB per day (upon waking, mid-morning, and at bedtime), while all other participants took placebo supplements on the same schedule.  All of the women completed the same whole-body resistance training program. 24 women completed the entire study as designed. In these women, fat free mass and muscle thickness increased in all three groups. However, only the TRF+HMB group significantly reduced fat mass (-7%) and significantly improved their body composition (-2.3 % body fat, an 8% improvement). These data show that HMB can help reduce body fat while maintaining muscle mass during intermittent fasting in active women.

β-Hydroxy-β-methylbutyrate and its impact on skeletal muscle mass and physical function in clinical practice: a systematic review and meta-analysis.

A systematic review and meta-analysis of fifteen randomized controlled trials was conducted to investigate the efficacy of HMB alone, or supplements containing HMB on skeletal muscle mass and physical function. After reviewing the evidence the authors concluded that HMB and supplements containing HMB increased muscle mass and strength in a variety of clinical conditions.