GLP-1 Receptor Agonists

GLP-1 (glucagon-like peptide-1) receptor agonists have transformed the metabolic optimization landscape. Originally developed as diabetes medications, compounds like semaglutide (marketed as Ozempic/Wegovy), tirzepatide (Mounjaro/Zepbound), and the investigational retatrutide work by mimicking the incretin hormones your gut releases after eating. These peptides enhance insulin secretion when blood sugar is elevated (glucose-dependent, meaning they do not cause hypoglycemia), suppress glucagon release, slow gastric emptying, and act on the hypothalamus to reduce appetite and food reward signaling.

Semaglutide, a once-weekly GLP-1 agonist, has been shown in clinical trials to produce 15-17% total body weight loss over 68 weeks. Tirzepatide, a dual GLP-1/GIP agonist, has demonstrated even greater efficacy with up to 22% body weight loss. Retatrutide, a triple-agonist targeting GLP-1, GIP, and glucagon receptors, has shown up to 24% body weight loss in Phase 2 trials. Clinical experts note that the weight loss itself is secondary to the metabolic improvements: reduced fasting insulin, improved lipid profiles, reduced liver fat, decreased inflammatory markers, and improved cardiovascular risk scores.

Dosing these compounds requires a slow titration to minimize gastrointestinal side effects (nausea, which typically resolves within 2-4 weeks at each dose level). Semaglutide starts at 0.25mg weekly, increasing monthly to a target dose of 1.0-2.4mg. Tirzepatide starts at 2.5mg weekly, increasing to a target of 5-15mg. The most common side effects are nausea, constipation, and reduced appetite. More serious but rare side effects include pancreatitis and gallbladder issues, which is why baseline and periodic monitoring of amylase, lipase, and hepatic function is recommended. These are prescription medications and should only be used under medical supervision.