GLP-1 Agonist (Semaglutide) — The Metabolic Regulator
Semaglutide is a long-acting glucagon-like peptide-1 (GLP-1) receptor agonist that profoundly improves metabolic health by regulating appetite, insulin secretion, and gastric emptying. Beyond weight loss and glycemic control, emerging evidence suggests it offers significant cardiovascular and neuroprotective benefits relevant to longevity.
Mechanism of Action
Semaglutide binds to and activates the GLP-1 receptor, a G-protein-coupled receptor expressed in the pancreas, brain, heart, and gut. In the pancreas, it enhances glucose-dependent insulin secretion and suppresses inappropriate glucagon release. Centrally, it acts on the hypothalamus and hindbrain to increase satiety and reduce food cravings. Downstream effects include reduced systemic inflammation, improved endothelial function, and potential modulation of mTOR and AMPK pathways secondary to caloric restriction and weight loss.
Human Trial Evidence
Extensive human trials demonstrate profound efficacy for weight loss and glycemic control (e.g., the STEP and SUSTAIN trial programs). The SELECT trial (2023, NEJM) showed a 20% reduction in major adverse cardiovascular events in overweight/obese adults without diabetes. Ongoing trials are investigating its neuroprotective effects in early Alzheimer's disease.
Dosing Protocol
For weight management, the typical maintenance dose is 2.4 mg injected subcutaneously once weekly, titrated up over several months. For type 2 diabetes, doses range from 0.5 mg to 2.0 mg weekly. Oral formulations are taken daily at 7-14 mg. Prescription required.
Safety & Contraindications
Common adverse effects include nausea, vomiting, diarrhea, and constipation, particularly during dose escalation. Contraindicated in individuals with a personal or family history of medullary thyroid carcinoma or Multiple Endocrine Neoplasia syndrome type 2 (MEN 2). Rare risks include pancreatitis and gallbladder disease. Prescription required.