GLP-1 medicines: the data, not the hype

Incretin medicines are the first peptide class in a generation that changed population-level practice. They are also the first to be treated like a lifestyle accessory. Those two facts should be held in the same hand.

What the trials measured

STEP 1 showed that weekly semaglutide 2.4 mg produced substantial mean weight loss versus placebo in adults with overweight or obesity, with a familiar GI adverse-event pattern. SELECT went further: in people with established cardiovascular disease and overweight, semaglutide reduced major adverse cardiovascular events. SURMOUNT-1 did analogous work for tirzepatide on weight, with larger average losses at the higher doses.

Those are not influencer results. They are randomized, placebo-controlled, regulator-reviewed programs. If you want 'peptides that have evidence,' start here.

What they did not make optional

• Gastrointestinal effects are common and sometimes treatment-limiting.
• Gallbladder events and a pancreatitis caution are on the labels.
• Rodent C-cell tumor findings produced a boxed warning and an MTC/MEN2 contraindication.
• Lean-mass loss travels with fat-mass loss. Resistance training and protein intake are clinical conversations, not biohacks.
• Weight typically returns when the drug is stopped. These are chronic medicines for chronic physiology.

Compounding is not a generic

During shortages, compounded semaglutide and tirzepatide filled a vacuum. A compounded product is not the approved pen. Salt forms, dosing errors, and sterility failures are documented problems. If the clinical case for an incretin is strong, the case for an unregulated vial is not automatically strong with it.

The evidence belongs to the approved products, in the studied populations, at the studied doses — not to whatever is in a research vial with a similar name.