In 2010, sarcopenia was defined and its diagnostic methods were provided by European Working Group on Sarcopenia in Older People. In 2016, sarcopenia was included in the new ICD-10-CM code, representing a major step forword in recognizing sarcopenia as a disease, and its attention gradually increased. Nutritional therapy is an important part of critical care medicine. Muscle loss is prevalent in ICU patients, especially in the elderly, and providing nutritional therapy can shorten the hospital stays and reduce the mortality rate. β-hydroxy-β-methylbutyrate possesses a unique mechanism of action - increases protein synthesis and reduces protein breakdown, making it a clinical nutritional supplementation already in the population in need of increasing muscle for many years, and there is a large number of research literature support. The group of people who need to increase muscle mass include older people, AIDS patients, cancer patients, or other patients with chronic diseases. For residents of the ICU, sarcopenia means not only weakness and malnutrition, but also increased the risk of death. Therefore, preventing and reducing muscle loss in hospitalized patients is one of the therapeutic factors that ICU doctors should consider. However, in the field of critical care medicine, little research has been done on HMB. By analyzing existing studies synthetically, it suggests that HMB is considered to be a nutritional supplementation and is worthy of use in ICU patients with muscle loss.