NCT07908940Enrolling by invitation
Changes in Body Composition Following Pharmacological Treatment for Obesity.
Assessment of Body Composition and Prevalence of Sarcopenia Following Intentional Weight Loss With Medications (Semaglutide or Tirzepatide) in People With Obesity
Source: ClinicalTrials.gov · Last updated 2 Nov 2026
Brief summary (registry, in English)
Background: Intentional weight loss via various treatments results in a loss of lean mass of approximately 10% for every 10 kg of total weight lost. There is a paucity of data regarding changes in skeletal muscle mass associated with the novel anti-obesity drugs becoming available-specifically concerning not only quantitative changes but also the potential impact on muscle strength and the ability to perform activities of daily living. Objectives: 1) To determine changes in body composition in individuals with obesity treated with semaglutide or tirzepatide for a period exceeding 6 months. 2) To analyze the impact of these changes on muscle strength and function. Methodology: A prospective, multicenter study coordinated by the Obesity Section of the Spanish Society of Endocrinology and Nutrition (SEEN). The study includes individuals with obesity (without diabetes) undergoing pharmacological treatment with semaglutide or tirzepatide. Body composition is analyzed via bioimpedance before and after treatment. Muscle strength is assessed using handgrip dynamometry and the chair-stand test. Exploratory analyses cover weight loss percentage, weight loss categories, changes in fat mass and fat-free mass (kg and %), and estimates of total and appendicular skeletal muscle mass. Optional sub-studies include abdominal ultrasound (to measure subcutaneous and preperitoneal adipose tissue thickness) and ultrasound of the rectus femoris muscle. Data on side effects, diet, exercise, and quality of life are also recorded. Planned analyses include weight loss percentages, changes in variables following pharmacological treatment, adjustments for confounding variables (age, sex, protein intake, structured physical activity, etc.), and exploratory uni- and multivariate logistic regression analyses.
- Status (registry)
- Enrolling by invitation
- Study type
- Observational
- Enrollment
- 116 (estimated)
- First submitted
- 26 Oct 2026
- Start date
- 1 Sept 2025
- Primary completion date
- 30 Sept 2026
- Lead sponsor
- Hospital San Carlos, Madrid
- Diseases
- Obesity
- NCT number
- NCT07908940
What you commit to
- Study type: Observational
- Planned participants: 116
- From 1 Sept 2025 to the primary completion date, 30 Sept 2026
- 1 site in 1 country
- Visits and tests: ask the trial team, the registry does not list them
Built from the registry fields of ClinicalTrials.gov. It describes the study, not your situation.
Who cannot take part
Copied verbatim from ClinicalTrials.gov and grouped by topic. Only the trial team decides who can take part.
Prior treatment
- Individuals who use the medication intermittently.
- Individuals who switch between different anti-obesity medications during the observation period.
Other illness
- Type 1 diabetes
- Type 2 diabetes
- Inability to follow an exercise regimen (e.g., due to disabling arthropathy, advanced COPD, skeletal or muscular impairments, or the aftereffects of a stroke, etc.) that prevents effective physical exercise (whether aerobic and/or strength-based).
- Presence of disabling cardiovascular disease (unstable coronary artery disease, NYHA Class IV heart failure).
- Advanced liver disease (Child-Pugh class B or higher).
- Major psychiatric illness (depression, eating disorders, psychosis, obsessive-compulsive disorder, personality disorders, etc.).
- Allergy to any of the components of the selected medication.
- History of acute pancreatitis or gastroparesis.
- History of MEN-2A (Multiple Endocrine Neoplasia type 2A) or medullary thyroid carcinoma.
Lab values
- Advanced renal impairment (eGFR \< 15 ml/min).
Other
- Pregnancy and breastfeeding
- Individuals who do not reach the maximum tolerable dose of treatment (defined as the highest dose that does not cause side effects), provided that the dose is at least 1 mg of semaglutide or 5 mg of tirzepatide per week.
Who the study is looking for
- Subjects of both sexes, aged 18-80 years, with BMI ≥ 30 kg/m2, who are starting pharmacological treatment for the first time (or who have been without treatment with GLP1 analogues for at least 6 months).
- Individuals with a BMI ≥ 30 kg/m² and weight regain of ≥ 15% following the nadir weight achieved after bariatric-metabolic surgery.
- Pharmacological treatment: patients with the capacity to undertake a long-term (minimum 6 months), self-funded treatment regimen with semaglutide or tirzepatide.
- Signing of an informed consent form.
Age in the registry: 18 years to 80 years · Sex: All · Does not accept healthy volunteers
Sites (1)
Sites in registry order. Pick your city on the disease page to sort them by distance.
| Site | City | Country | Site status |
|---|---|---|---|
| Hospital Clínico San Carlos Coordinator of this site? Confirm its status | Madrid | Spain | Unknown status |
This page is information, not medical advice. Discuss any trial with your doctor.