Therefore, undernutrition is common in the elderly where its prevalence varies from 4 to 10% at home, from 15 to 30% in care homes and reaches 30 to 70% in hospitals de-pending on the diagnostic criteria used [10]. Most of all, aging impairs the ability to adapt to undernutrition leading to severe loss of body weight and muscle [11-14]. In particular, old rats exhibit defective adaptation to long-term 50% dietary restriction initiated at an advanced age, resulting in dramatic body weight loss and deregulation of protein metabolism in terms of nitrogen balance and protein content, especially at skeletal muscle level [12]. Therefore, in elderly patients, undernutrition exacerbates the state of frailty and dependence, greatly increasing the risk of morbidity and mortality [15]. This is even more critical that the world aging population is growing up. Accord-ing to United Nations statistics on the demographic trend in aging population, the proportion of persons aged 65 or over in the world is projected to reach nearly 16% in 2050, compared to 9% in 2019 [16]. Specific studies are needed to better understand the undernutrition-induced skeletal muscle alterations in order to identify new therapeu-tic targets and prevent sarcopenia in the old population