Incretin mimetics are widely used pharmacological treatments for weight loss, known for their high efficacy and favorable safety profile. As the most commonly prescribed drug in this class, semaglutide is effective in both diabetic and non-diabetic individuals. However, treatment responses vary significantly, with non-diabetic individuals typically experiencing better weight loss outcomes. Despite this, up to 10% of non-diabetic individuals show little or no response to treatment, and the reasons for this variability remain unclear. The TRIM-IR study aims to investigate the role of insulin resistance (IR) in weight loss outcomes among non-diabetic obese individuals receiving semaglutide. This single-center, observational study will assess the impact of IR on weight loss, body composition, and adipose tissue function during the first 16 weeks of semaglutide therapy. The study will also explore molecular markers of adipose tissue dysfunction, focusing on the transition from dysfunctional to healthy adipose tissue. The investigators hypothesize, that individuals with lower IR will experience greater weight loss than those with higher IR, and that the glucose infusion rate (GIR) during hyperinsulinemic euglycemic clamp testing will correlate with weight loss variability. Secondary objectives include comparing changes in fat and lean mass, reductions in visceral fat, and improvements in adipose tissue function before and after 16 weeks of treatment. Exploratory analyses will assess adipocyte subpopulations and their response to insulin sensitivity changes. A total of 40 participants, equally distributed by gender, will be enrolled to ensure statistical power for detecting clinically relevant differences. The study aims to optimize semaglutide use for personalized obesity treatment and provide insights into the relationship between obesity, insulin resistance, and adipose tissue plasticity, with implications for improving obesity management and cardiovascular health outcomes.