Nutrition · Sep 28, 2026

Ultrasound-assessed changes in abdominal fat and subcutaneous fat over the rectus femoris and gastrocnemius after a partial meal-replacement program in adults with obesity

By Román DL, Perez P, Jauregui OI et al.

OBJECTIVES: Obesity is characterized not only by excess body weight, but also by abnormal regional adipose tissue distribution, which contributes to insulin resistance, dyslipidemia, and metabolic syndrome (MS). Ultrasound may provide a practical method for monitoring changes in abdominal and peripheral adipose depots during nutritional treatment. The objective of the study was to evaluate changes in ultrasound-assessed abdominal and limb subcutaneous fat depots after a partial meal-replacement (pMR) program in adults with obesity METHODS: This prospective, single-arm, before-after interventional study included adults with obesity undergoing a structured pMR program. Anthropometric parameters, dietary intake, biochemical variables, and MS components were assessed at baseline and after intervention. Ultrasound was used to measure total subcutaneous fat thickness (TSFT), preperitoneal fat thickness (PFT), and subcutaneous fat thickness over the rectus femoris and gastrocnemius regions (SFTRF and SFTG, respectively). Correlation and multiple regression analyses were performed to explore associations between ultrasound-derived changes and metabolic outcomes. RESULTS: Seventy-five adults with obesity completed the study. After 12 wk, body weight decreased by 9.1 kg, with significant reductions in body mass index, waist circumference, and fat mass. Total energy intake decreased from 1663.9 ± 431.7 to 1156.5 ± 220.8 kcal/d. Fasting glucose, insulin, homeostasis model assessment of insulin resistance, and triglycerides improved significantly. Hypertriglyceridemia decreased from 37.6% to 20.0%, pathological high-density lipoprotein cholesterol from 45.5% to 16.9%, and MS from 52.5% to 21.5%. Ultrasound showed significant reductions in total TSFT, PFT, and SFTRF. Changes in TSFT were related to triglyceride changes, and PFT was related to body weight change. In multivariable analyses, TSFT change independently predicted changes in insulin, homeostasis model assessment of insulin resistance, and triglycerides, whereas PFT change independently predicted body weight change. CONCLUSIONS: A 12-wk pMR program improved anthropometric and cardiometabolic risk markers, and produced measurable reductions in ultrasound-assessed abdominal and limb adipose depots. Ultrasound may be a useful complementary tool for monitoring adipose tissue during obesity treatment.

doi.org/10.1016/j.nut.2026.113443PubMed 42914708Interventions