Preservation of muscle mass assessed by ultrasound during a meal replacement-based hypocaloric intervention in obese individuals: a real-world clinical trial.

Abstract

Introduction: Background: meal replacement (MR) diets involve substituting one or more regular meals with specially formulated nutritional products. This 12-week intervention aimed to assess the impact of a hypocaloric meal replacement on body weight and metabolic parameters, emphasizing muscle mass evaluation by ultrasound Methods: a real-world study was conducted using a MR diet protocol, one daily meal was replaced with a nutritional formula. Anthropometric and biochemical parameters were assessed at baseline and after 12 weeks, along with ultrasound-based measurements of the rectus femoris and gastrocnemius medialis muscles to monitor changes in muscle mass. Results: the study population had a mean age of 59.3 ± 9.1 years and included 18 males (28.1 %) and 46 females (71.9 %). After 12 weeks of intervention, significant reductions were observed in body weight, body mass index, fat mass, waist circumference, serum triglycerides, LDL cholesterol, fasting glucose, insulin, and HOMA-IR. Additionally, there was a notable decrease in the prevalence of metabolic syndrome, central obesity, hypertriglyceridemia, hypertension, and hyperglycemia. Ultrasound assessments revealed a significant increase in rectus femoris muscle area (RFMA) (4.40 ± 0.6 cm² to 5.86 ± 0.4 cm²; p = 0.04), and in rectus femoris muscle thickness (RFMT) (1.70 ± 0.3 cm to 2.32 ± 0.3 cm; p = 0.03), indicating a preserved or enhanced muscle morphology despite overall weight loss. Conclusions: this study shows that a structured MR program effectively reduces body weight and improves metabolic parameters in individuals with obesity. Notably, muscle mass -especially in the rectus femoris- was preserved or improved.