Every week, someone asks me a version of the same question: what does the evidence actually say? Not the influencer version. Not the drug-rep version. The trials.

The problem is that the honest answer lives across a dozen studies, three drug classes, and about forty footnotes. So I did the compression for you. Twelve trials, ten sections, one page: the GLP-1 Evidence Cheat Sheet. It's free, and the download link is below.

Here's the part of it I most want you to sit with.

You've seen the headline numbers. Tirzepatide, about 20% mean weight loss in SURMOUNT-1. Semaglutide, about 15% in the STEP program. Retatrutide tracking toward 24% in phase 2, still investigational as I write this.

Those are real. They're also averages, and averages are the least interesting numbers in the dataset. Roughly 30-50% of tirzepatide patients lose 20% or more of their body weight. A smaller fraction lose under 5%. Same drug, same dose, wildly different bodies. Genetics, baseline metabolic rate, food environment, behavior. They all bend the curve.

So the myth that should die: "everyone loses the same on these drugs." Nobody loses the same. If you start therapy expecting the trial mean and land somewhere else, that's not failure. That's the response curve doing exactly what it always does.

SELECT is the trial that changed the conversation. Semaglutide in 17,604 adults with cardiovascular disease and obesity but without diabetes, followed for roughly 3.3 years: a 20% relative reduction in major cardiovascular events. That composite is cardiovascular death, non-fatal heart attack, and non-fatal stroke.

The detail that matters most: the benefit started separating before peak weight loss. If this were purely a weight-loss effect, the curves wouldn't move until the weight did. They moved earlier. That points to mechanisms working alongside weight: blood pressure, inflammation, triglycerides, direct vascular effects.

The myth that should die: "GLP-1s only help because of weight loss." The timing in SELECT doesn't fit that story.

And the cardiometabolic evidence keeps widening. FLOW (semaglutide in diabetic chronic kidney disease) was stopped early for efficacy: a 24% reduction in major kidney disease events, plus a significant drop in cardiovascular mortality. In heart failure with preserved ejection fraction, a condition we've treated with little more than diuretics for years, STEP-HFpEF and SUMMIT both delivered real symptom and event benefits for the obesity phenotype. SUMMIT alone showed a 38% reduction in worsening heart-failure events or cardiovascular death.

Yes, GLP-1 patients lose lean mass. Across the STEP and SURMOUNT DEXA data, roughly 25-40% of total weight loss is lean mass, which is about what you see with caloric restriction and no medication at all.

That's the whole point. The myth that should die: "GLP-1s cause uniquely catastrophic muscle wasting." Compared to equivalent weight loss by other means, they don't.

But "not unique" is not "doesn't matter." Resistance training two to three times a week and protein intake of at least 1.2 g/kg/day each blunt lean-mass loss in nearly every study we have, and together they beat either one alone. The loss isn't pathologic. Complacency about it can be.

STEP 4 and SURMOUNT-4 tell the same story. Stop the drug without a plan, and most of the weight comes back: roughly two-thirds of it within a year in the semaglutide withdrawal data.

This is a chronic disease, and these are chronic therapies. The myth that should die: "use it as a kickstart, then stop." For most people, that isn't how the physiology works. Regain after stopping isn't a moral failing. It's the disease reasserting itself. Plan for it.

The full cheat sheet covers all ten: the pivotal weight-loss trials, SELECT, FLOW, the HFpEF data, muscle loss, side effects by actual frequency (most are mild, transient, and titration-responsive), what happens when you stop, the compounding and telehealth landscape, and seven questions worth bringing to your next appointment. Every number comes from the peer-reviewed publication of the listed trial.

It's built to be scanned like a chart. Print it, keep it, bring it to a visit.

Each section compresses a full deep dive from the archive. If one of them raises a question, the long version is a click away, with the methods, limitations, and all the footnotes.

Talk soon,
Michael

Michael Albert, MD. Board-Certified Obesity Medicine Physician.

This is educational and not medical advice. Individual decisions about GLP-1 therapy should be made between a patient and their clinician, considering full medical history, contraindications, and goals of care. The author is Chief Medical Officer of Vineyard, a telehealth obesity medicine practice.