Researchers gave semaglutide, the drug in Ozempic and Wegovy, to elderly female mice, and the treated mice lived about 12 percent longer than the ones that went untreated. That is close to 100 extra days of a mouse life. They also did better on tests of muscle function, thinking and spatial memory.
The honest version of that finding is narrower than the headline it is going to get. This was a study in mice, and a mouse lifespan study does not show that a person taking semaglutide will live longer or age more slowly. The researchers are now looking at whether the drug is acting on inflammation and other pathways tied to age related decline, which is the part that would eventually matter for people. That work has not been done yet.
Muscle came up again this week from a different direction. A review of the GLP-1 trials, including Novo Nordisk's STEP 1 trial of semaglutide, found lean body mass accounted for 25 to 39 percent of the total weight people lost. That is not unique to these drugs, it happens with most weight loss, but it is worth watching in older adults, in menopausal women and in anyone already low on muscle, because losing too much of it affects balance, strength and how well someone moves. Resistance exercise and enough protein are still the two things that protect it.
A study in Clinical Nutrition described 15 reported cases of Wernicke encephalopathy in people taking GLP-1s. It is a rare brain condition caused by a severe deficiency of vitamin B1. Most of the people in those reports had gastrointestinal or nutrition problems first: vomiting, loss of appetite, malnutrition. The researchers say plainly that 15 case reports cannot show the medication caused it, and they have asked for more work before anyone draws a conclusion. What it does underline is that eating very little for months on end has consequences of its own.
And the number of bariatric surgeries in the United States fell below 200,000 in 2024, the first time since 2020 and a drop of more than 20 percent in a year. The Baton Rouge Advocate followed one woman through the other direction: GLP-1 injections made her sick, so she had a sleeve gastrectomy instead, and she has lost 115 pounds, 87 of them after the surgery.
Four studies, four different questions, and none of them settles anything on its own. The lifespan result is early and it is in mice. The muscle and vitamin findings are the ordinary maintenance side of being on one of these drugs, the part that gets less attention than the scale does.
Key details
Semaglutide extended the lifespan of elderly female mice by about 12 percent, close to 100 extra days, and the treated mice did better on muscle, cognitive and spatial memory tests.
The study does not show that people taking semaglutide will live longer or age more slowly.
Lean body mass accounted for 25 to 39 percent of total weight lost in GLP-1 trials, including STEP 1. Resistance exercise and enough protein help protect it.
A Clinical Nutrition study described 15 reported cases of Wernicke encephalopathy, a rare vitamin B1 deficiency condition, in people taking GLP-1s. Most had vomiting or appetite loss first, and the report does not prove the drugs caused it.
Bariatric surgery in the United States dropped below 200,000 procedures in 2024, down more than 20 percent from the year before.
Sources
Medscape: Muscle Loss on GLP-1s: Data and Debate
Fox News: Ozempic and Wegovy may cause rare brain disorder, new study warns
Baton Rouge Advocate: In GLP-1 era, this Baton Rouge couple chose surgery instead
Originally published on GLP-1 Nation.
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