Hi {{first name | there}},

If Ozempic could help you live longer, would you take it even if you didn’t need to lose weight?

A year ago, I wrote about people trying microdoses of GLP-1 drugs for longevity. There was plenty of enthusiasm and very little evidence at the time.

Now there’s something more interesting: a study in which old mice given semaglutide, the drug in Ozempic and Wegovy, lived longer. The researchers also asked whether the benefit came from simply eating less.

The human studies, meanwhile, have revealed a few surprises: heart benefits, a failed Alzheimer’s trial, and fitness gains the drug alone didn’t deliver.

Below, I'll dig into the latest in GLP-1 agonists for longevity and healthspan.

This Nature study measured lifespan. No biological-age calculator required.

Researchers started semaglutide in 20-month-old female mice. The animals in the lifespan experiment stayed on treatment for the rest of their lives and outlived controls. Separate groups showed improvements in memory and physical function.

But the real question is: did semaglutide help because the mice ate less?

In a separate experiment, researchers compared semaglutide with a diet containing 24% fewer calories. Both groups lost similar amounts of weight and fat. Several benefits overlapped; some measures, including spatial memory and glucose control, favored semaglutide.

But the diet group ate quickly and then fasted; the drug group ate gradually. Feeding patterns could explain some of the differences. Also, this experiment compared function, not lifespan.

So interesting as an idea-generating study, but not yet a home run.

SELECT enrolled 17,604 people with overweight or obesity and established cardiovascular disease, but no diabetes. Over about 3.3 years, 6.5% on semaglutide had a cardiovascular death, nonfatal heart attack or nonfatal stroke, versus 8.0% on placebo.

About 15 fewer people per 1,000 had one of these events. SELECT primary publication; 17,604 adults with overweight or obesity and existing cardiovascular disease, without diabetes.

However, “without diabetes” doesn’t mean totally healthy. Everyone in SELECT had cardiovascular disease. These numbers don’t tell a lean, low-risk person what they’d gain, or prove that semaglutide slowed aging.

Importantly, side effects led 16.6% of the semaglutide group to stop the study drug, compared with 8.2% on placebo.

Preventing cardiovascular events is fantastic. Whether the drug slows aging is a separate question. Some researchers have started testing that through biological-age measures.

Researchers analyzed blood samples from 84 participants in a 32-week randomized trial in people with HIV-associated excess abdominal fat.

They used “aging clocks”: tools that read chemical marks on DNA to estimate biological age or how fast someone is aging. On DunedinPACE, which estimates the pace, semaglutide lowered the score by 0.09 units versus placebo. The authors describe that as roughly 9% slower estimated aging over the 32-week study.

Other clocks, including PhenoAge and PCGrimAge, also shifted toward younger age estimates relative to placebo.

This was an exploratory analysis added after the trial design, and the researchers tested multiple clocks without adjusting for multiple comparisons, which raises the chance of false-positive findings. An earlier, smaller SLIM LIVER analysis also reported clock changes, but had no placebo group.

My read: exciting findings, but I wouldn’t place much confidence in them yet.

Brain health gives us a less encouraging result. Across evoke and evoke+, two randomized trials with 3,808 participants, oral semaglutide did not slow early Alzheimer’s disease at two years.

So semaglutide didn’t help slow established Alzheimer’s in these trials. Whether earlier treatment could prevent dementia remains an open question, however.

These studies tested different outcomes in different populations. A better aging score doesn’t establish longer life, and a disease-treatment trial doesn’t establish prevention.

For healthspan, there’s another practical question: as we lose weight, what happens to muscle, strength and fitness?

A 2026 analysis of a randomized trial in 193 adults with obesity followed people for a year after an initial diet. Exercise plus liraglutide improved aerobic fitness and stair-climbing more than liraglutide alone. Exercise alone produced similar gains; adding the drug didn’t show a clear fitness advantage over exercise.

Liraglutide is an older GLP-1. This S-LiTE analysis compared aerobic-fitness changes with placebo after a year of treatment. It did not establish a fitness advantage from adding the drug to exercise.

A new review found that GLP-1 treatment reduced lean mass across 28 studies involving 1,765 people. The evidence was low-certainty.

Lean mass isn’t just muscle, and fewer studies measured strength or performance. We still don’t know how often those changes leave people weaker.

That’s why I’d track what you can lift and how you move, alongside what you weigh.

It’s still too early to start recommending a GLP-1 agonist as a general longevity drug.

For obesity, diabetes or another established indication, the benefits may already justify treatment. In fact, it feels very much like a miracle class of drugs.

For a metabolically healthy person considering microdosing, the basic questions remain: does it extend life, what dose would work, and would the benefit outweigh the side effects? We don’t have those answers yet, and I’m still on the fence about the practice, especially if metabolic biomarkers look great already.

Until next time,

Hillary Lin, MD

Your Workout Might Be Making You Older

How do you train for healthspan without making recovery a second job? Performance coach Kyle Gonzalez and I discuss strength, cardio and rest. Start at 19:46 for HIIT versus Zone 2 when you’re short on time.

Watch the full conversation

Science of Skin Summit, September 17–20, Austin, TX. I’m speaking on AI in dermatology and on skin and hair as windows into biological age.

MVMNT Longevity Summit, September 22–23, Coronado, CA. I’m leading a session on turning longevity data into clinical action. Use code JOINME10 for 10% off registration.

Livelong Women’s Health Summit, September 25–26, Hilton Midtown, New York City. I’m moderating four panels and joining the closing audience Q&A.

Her Longevity, October 3, New York City. I’m joining the speakers for a day focused on women’s longevity medicine.

Science of Skin Longevity Summit, February 19–21, 2027, Scottsdale, AZ. I’m joining the faculty for a practical skin-longevity talk and the peptides panel.

If seafood is already on your shopping list, Seatopia offers $20 off your first order with code HILLARYLINMD.

Browse all partner offers. Purchases through affiliate links may earn me a commission and help support this Letter.

Not sure which tests would change your plan? My guides explain what they measure, when they help and where they mislead.

Explore the testing guides.

Have a topic request? Reply here—please leave out private medical details.

Forwarded this email? Get The Longevity Letter.