Increased fat accumulation may be associated with severe muscle wasting in critically ill patients: a prospective observational study

Obesity has been hypothesized to attenuate muscle wasting in critically ill patients due to increased ketogenesis. This study examined the associations between fat mass volume, ketone bodies, and muscle wasting in critically ill patients. We conducted a prospective study in an emergency intensive care unit (ICU) from November 2021 to October 2023, enrolling adult patients with an expected ICU stay of ≥ 7 days and abdominal computed tomography (CT) performed within 24 h of admission. Patients were classified as adipose or lean based on fat area measured via CT. The primary outcome was severe muscle wasting, defined as a > 10% decrease in the rectus femoris cross-sectional area measured by ultrasonography from day 1 to day 7. Among 134 enrolled patients, 108 were evaluable (57% male, median age 73 years). Severe muscle wasting was more frequent in the adipose group (48%) than in the lean group (27%, p = 0.023). Multivariate analysis confirmed a higher risk of muscle wasting in the adipose group (adjusted OR 2.52, p = 0.034). BHB levels were inversely correlated with fat area and associated with a reduced risk of muscle wasting. Contrary to our hypothesis, obesity increased the risk of muscle wasting, potentially due to decreased ketogenesis.200/200 words.