At a Glance

GLP-1 receptor agonists (semaglutide and tirzepatide) are approved for type 2 diabetes and obesity. They increase glucose-dependent insulin secretion, suppress glucagon release, slow gastric emptying, and increase satiety, making them powerful metabolic tools. Supply shortages have driven compounded versions, but FDA has warned about safety risks with compounded semaglutide.

What It Is

Semaglutide and tirzepatide are peptide hormone analogs that activate GLP-1 receptors. Semaglutide is available as both a subcutaneous injection and an oral tablet (Rybelsus); tirzepatide is administered as subcutaneous injection only. Tirzepatide is a dual GLP-1/GIP receptor agonist (more recent), while semaglutide is GLP-1-selective. Both slow gastric emptying, increase glucose-dependent insulin secretion, suppress glucagon release, and promote satiety through central appetite centers.

How It Works

GLP-1 agonists bind GLP-1 receptors on pancreatic beta cells, enhancing glucose-dependent insulin secretion and suppressing glucagon secretion from alpha cells. They slow gastric emptying, reducing postprandial glucose spikes and promoting satiety by signaling fullness to the brain. Tirzepatide additionally activates GIP receptors, enhancing metabolic benefits.

Key Benefits

  • Powerful, sustained weight loss (up to 15–22.5% body weight in clinical trials, depending on agent and dose)
  • Improved blood glucose control and HbA1c reduction
  • Cardiovascular benefits beyond glucose control (SELECT trial: 20% MACE reduction with semaglutide; LEADER trial: CV benefit with liraglutide)
  • Reduced appetite and food cravings
  • Once-weekly or once-daily convenient dosing

Who It's For

  • Individuals with type 2 diabetes seeking glycemic control
  • Those with obesity seeking sustainable, medically-supervised weight loss
  • Metabolically compromised individuals seeking improved insulin sensitivity and body composition
  • Individuals at high cardiovascular risk or with metabolic syndrome

Typical Use

Semaglutide is dosed at 0.25–2.4 mg weekly by subcutaneous injection; tirzepatide at 2.5–15 mg weekly. Both are titrated gradually over 4–8 weeks to minimize gastrointestinal effects. Duration is typically indefinite for chronic disease management.

Important Safety Information

  • Supply shortages have driven use of compounded semaglutide; FDA has issued warnings about compounded product safety
  • Gastrointestinal side effects (nausea, vomiting, diarrhea) are common, especially early in therapy
  • BOXED WARNING: Risk of thyroid C-cell tumors (based on rodent studies). Contraindicated in patients with personal or family history of medullary thyroid carcinoma (MTC) or MEN2 syndrome. Risk of pancreatitis. Gallbladder disease and cholelithiasis reported in clinical trials. Retinopathy worsening reported with semaglutide (SUSTAIN-6 signal).
  • Potential for rapid dehydration and acute kidney injury in some patients

Global Regulatory Status

Note: Supply shortages have driven compounded versions; FDA has specifically warned about the safety risks of compounded semaglutide. Approved pharmaceutical-grade products are strongly preferred.

The Bottom Line

Semaglutide and tirzepatide are potent metabolic tools with proven efficacy for diabetes and obesity. Weight regain is expected after discontinuation (studies show ~60% of lost weight regained within one year of stopping GLP-1 RAs). However, supply shortages have created an unregulated compounded market. Approved products are preferred; compounded versions carry uncertain safety profiles.

This guide is for educational purposes only and does not constitute medical advice. Always consult a qualified healthcare provider before starting any supplement or medication.