Positives

• One individual noted that after incorporating HMB into their routine, they experienced a gradual improvement in their symptoms, with benefits “compounding” and becoming “better each week” Reddit.
  
  

Negatives

• Memorial Sloan Kettering notes HMB evidence for muscle preservation is largely confined to older adults and untrained subjects under high physical stress; benefits for athletes and patients without baseline sarcopenia are lacking, making it an unlikely fit for most Long COVID deconditioning. Memorial Sloan Kettering.
• Examine.com summarizes side effects as generally mild and limited to GI discomfort - heartburn, upset stomach, nausea, and flatulence at the typical 3-6 g/day dose, with no benefit found for muscle outcomes in many trials. Examine.com.
• Healthline reports that for healthy younger adults and trained athletes, HMB supplementation has not produced consistent benefits in strength or muscle mass, while powdered formulations are described as having a notably bitter, sour taste that's hard to mask. Healthline.

Hurdles & Side Effects

• One individual reported developing additional upper gastrointestinal symptoms, such as “gastroperesis” and “occasional gagging/vomiting,” after starting HMB Reddit.