Novo Nordisk and Eli Lilly both told an aging research meeting in Boston that their weight-loss drugs appear to lower molecular "aging clock" readings, according to a news report on the presentations. MIT Technology Review covered the Aging Research and Drug Discovery meeting on Oct. 6, and the word doing the work in both companies' framing is "appear."

The drugs are semaglutide, sold as Ozempic and Wegovy, and tirzepatide, sold as Mounjaro and Zepbound. An aging clock is a mathematical model that compares a person's blood proteins or DNA marks against patterns from large populations and returns an estimated "biological age."

Key numbers

Novo's preprint, posted on Research Square, analyzed blood proteins from 10,052 people across five placebo-controlled semaglutide trials including SELECT and FLOW, with follow-up of up to 156 weeks. Compared with placebo, semaglutide was linked to a heart biological age roughly two to four years younger, with clocks for kidney, brain, pancreas, lung and whole body showing reductions of one to four years.

The authors reported those shifts were not fully explained by weight loss, blood sugar changes or lower inflammation. Lilly's tirzepatide work was smaller and used epigenetic clocks, with aging research vice president Kevin Duffin telling MIT Technology Review the clocks tell "a consistent story that we're seeing a reduction in age."

Why a clock is not an outcome

Neither dataset has cleared peer review: Novo's is a preprint, Lilly's was a conference presentation. Novo's own authors wrote that the findings stop short of "establishing biological rejuvenation," and they did not establish that the clocks are valid stand-ins for real health outcomes.

The analyses were also done after the fact on trials designed for other questions, and several Novo authors are company employees holding shares. That is not disqualifying, but it is the context in which a drugmaker's own longevity data arrives.

The gap this opens

Insurance generally does not cover these drugs for longevity, which pushes interested buyers toward cheaper online sellers. The FDA has warned that unapproved and compounded versions may contain the wrong dose or harmful ingredients, and as of May 31, 2026 had logged 990 adverse event reports tied to compounded semaglutide and more than 730 tied to compounded tirzepatide.

UCLA's Steve Horvath, credited with inventing aging clocks, called the results "a pretty strong effect" but said he has not seen sufficient evidence the drugs would benefit "skinny people." Researchers at the meeting also flagged side effects including muscle loss.

Bottom line

The approved indications have not moved: type 2 diabetes, obesity, and related heart and kidney risk, not slowing aging. ARPA-H has committed up to $38 million to a UT Health San Antonio trial testing semaglutide, dapagliflozin and rapamycin in adults in their 60s, with recruitment set for 2027, and that is where an answer for healthy people would actually come from.