Body composition is a key component for maintaining health and is associated with risk of disease as well as clinical outcomes. Routine assessments of hospital patients using body weight and body mass index by dietitians can provide inaccurate assessment of body composition. Ultrasound has emerged as a promising bedside tool for assessing muscle in clinical nutrition, offering advantages in accessibility and cost compared to traditional imaging modalities such as Magnetic Resonance Imaging (MRI). This study aimed to assess the validity of dietetic-led ultrasound muscle thickness measurement versus MRI gold standard in healthy participants.