Effect of Tirzepatide on Brown Adipose Tissue in Obesity

This study is testing whether a new anti-obesity medicine called tirzepatide can increase the activity of special fat cells in the body that help burn energy. These fat cells are known as brown and beige fat. The study includes women with obesity and will last 24 weeks. Participants will receive either tirzepatide or a placebo (a look-alike injection with no active drug). Researchers will measure the amount and activity of brown fat using medical imaging (PET/CT, MRI, and thermal camera), and examine fat tissue samples to look for changes in gene activity and structure that show beige fat activation. The study will also evaluate how these fat changes affect body weight, energy use, hormone levels, blood sugar, and other health markers. The goal is to learn whether tirzepatide helps improve metabolism by increasing energy-burning fat in addition to reducing appetite.

Inclusion Criteria: * Female sex * Age between 18 and 50 years * BMI between 30 kg/m² and 40 kg/m² at pre-screening * Prior comprehensive non-pharmacological and non-surgical management of obesity, including a history of at least 12 months of intensive lifestyle intervention with a maximum weight reduction of less than 5% * Stable body weight within the three months preceding study enrollment (defined as weight fluctuations within 5%) * No prior pharmacological or surgical interventions for obesity * Euthyroid state * Eumenorrhea or Oligomenorrhea * Ability to comprehend the study objectives and procedures * Willingness to provide informed consent and to comply with the study protocol, including the use of highly effective contraception during the study period, with signed consent and agreement provided in duplicate * Commitment to use highly reliable contraception and absence of plans for pregnancy within the 8 months following enrollment Exclusion Criteria: * Pregnancy or lactation * Postmenopausal * Amenorea * Type 2 diabetes * Reliance on natural contraception methods * Non-compliance with previous therapeutic regimens * Personal history of malignancy * Personal or family history of medullary thyroid carcinoma * Personal history of pancreatitis * Personal history of cholelithiasis * Personal history of major depressive episodes or suicidal ideation * Personal history of acute coronary events or hemodynamically significant coronary artery disease * Psychiatric disorders * Current treatment with sympathomimetics or sympatholytics * Excessive alcohol consumption