alt Hacker NewsI'm always confused with these type of posts because I feel the scientists must know something I don't. Why is it always does GLP-1 help with [general health thing]?
If I understand it correctly, GLP-1 drugs help people with weight loss. People are more healthy when they're not overweight, and GLP-1s help people get down to a healthier weight. So when we ask questions about do GLP-1s help this or that, isn't there a giant confounding variable here? That being overweight causes a litany of health issues has been common knowledge forever now. Thus, my (uninformed, intuitive) guess would just be that GLP-1s, which cause weight loss, also include the subsequent effects of healthy weight loss.
So why are we surprised then that people going from overweight to a healthy weight slows aging, or betters cardiovascular health as I've seen elsewhere? Aren't these already well-studied effects of healthy weight loss? Shouldn't these positive effects obviously just be attributed to weight loss, rather than the thing that causes the weight loss? And why are there articles about this stuff acting like this is unexpected?
I admit I'm a laymen and I hope don't sound too snide or critical here. I'm just kind of puzzled by this out of genuine curiosity.
Replies
1. Yes, for many of the benefits of GLP-1s, it's plausible the mechanism is weight loss. But actually achieving significant weight loss with other therapies is incredibly hard, so I think GLP-1s get some credit here.
2. Hunger signalling isn't the only thing GLP-1s do, so no, we should not just assume every effect stems from weight loss alone. E.g. the blood sugar regulation that makes them very effective for diabetes is not purely about weight management.
There is another plausible causal mechanism: weight gain flowing from hunger/metabolic dysregulation. This dysregulation being caused by some "factor X" which also causes other problems.
GLP-1 then addresses factor X, and the problems it causes, including weight gain.
Not that obesity doesn't independently cause problems but very plausible causality runs more than one way.
These studies control for such variables, confounding effects are easy to think of, but 9/10 times here on HN, the authors DID control and adjust for that confounder, the commenters just didn't read the methods.
When you see reporting like this it means there was some study that had some evidence of some effect that somewhat matches the description in the headline, but nothing more than that. How good of a study it was, how large the effect, how in alignment or not it is with a body of evidence, how reproduceable it is, how exaggerated the press release is. Are all left out and are all critical to how much anyone should care about the statement. What it definitely does not mean is "all scientists are asserting this truth in the headline"
Glp1s aren't just appetite suppressants. Two identical people doing and eating identical things -one on glp1 and one not - the one on willose more weight and have better biomarkers like insulin sensitivity
GLP-1 probably reduces systemic inflammation, with far-reaching consequences. That is a much bigger effect than just losing weight, though weight loss contributes to that.
Then there are the mental effects, such as people reporting that they lost various addictive habits (gambling, compulsive shopping etc.)
>“GLP-1 receptor agonists are being shown to benefit many chronic diseases over and above their effect on weight,” John Deanfield, FRCP, FESC, professor of cardiology at the Institute of Cardiovascular Sciences at University College London, told Medical News Today. “These include liver diseaseTrusted Source, kidney diseaseTrusted Source, diabetes, and neurological diseasesTrusted Source such as Parkinson’s diseaseTrusted Source. They should therefore not be labeled merely as ‘weight loss’ drugs, but as drugs that can have a direct effect to improve patients’ health.”
>Building off this research, Deanfield is the lead author of a new study recently published in the journal The LancetTrusted Source that provides further evidence of semaglutide and lowered major cardiac event risk, regardless of how much weight a person loses while taking the GLP-1 medication.
>“Semaglutide has previously been shown in the SELECT trial to significantly reduce major adverse cardiovascular events in overweight/obese patients with known heart disease but without diabetes,” Chen explained. “This study analyzed the information from the SELECT study, and found that this benefit to cardiovascular health did not depend on how overweight patients were or how much weight they lost.”
>“This interesting finding suggests that the cardiovascular benefits of semaglutide act through a biochemical mechanism not dependent simply on changing the body weight of an individual,” he continued. “This may open up other avenues of research and therapies that could improve heart health.”
https://www.medicalnewstoday.com/articles/weight-loss-drug-h...
Yeah!
These scientists, whose job it is to think about this really hard, why didn't they just think of the most obviously obviously thing? I'm sure they didn't!
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Dude. Come on.
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As another person commented, we currently believe the primary mechanism behind the pleitropic effects of GLP-1's to be a reduction in systemic inflammation and direct improvements in vascular/endothelial function.
The best paper I've seen on this was the recently published and very aptly named:
"Pleiotropic effects of GLP-1 receptor agonists — a narrative review of extra-metabolic outcomes in adults" (2026)
https://journals.viamedica.pl/medical_research_journal/artic...