Tirzepatide for Weight Loss: Can Medical Therapy "Outweigh" Bariatric Surgery?

The worldwide prevalence of obesity has been increasing progressively over the past few decades and is predicted to continue to rise in coming years. Unfortunately, this epidemic is also affecting increasing rates of children and adolescents, posing a serious global health concern. Increased adiposity is associated with various comorbidities and increased mortality risk. Conversely, weight loss and chronic weight management are associated with improvements in overall morbidity and mortality. The pathophysiology of obesity is multifactorial with complex interactions between genetic and environmental factors. The foundation of most weight loss plans is lifestyle modification including dietary change and exercise. However, lifestyle modification alone is often insufficient to achieve clinically meaningful weight loss due to physiological mechanisms that limit weight reduction and promote weight regain. Therefore, research has focused on adjunctive pharmacotherapy to enable patients to achieve greater weight loss and improved chronic weight maintenance compared to lifestyle modification alone. Glucagon-like peptide-1 receptor agonists (GLP-1RAs) are incretin hormone analogs that have proven effective for the management of type 2 diabetes mellitus as well as obesity and overweight. Tirzepatide is a novel "twincretin" that functions as a dual glucose-dependent insulinotropic polypeptide and GLP-1 RA. Tirzepatide was recently approved by the Food and Drug Administration for the management of type 2 diabetes. Similar to previously approved GLP-1RAs, weight loss is a common side effect of tirzepatide which prompted research focused on its use as a primary weight loss therapy. Although this drug has not yet been approved as an antiobesity medication, there are several phase 3 clinical trials that have demonstrated superior weight loss efficacy compared with previously approved medications. This review article will discuss the discovery and mechanism of tirzepatide, as well as the completed and ongoing trials that may lead to its approval as an adjunctive pharmacotherapy for weight loss.