Independent GLP-1 journalism
The science, plainly
The science, in plain English. How these drugs work, what they do to the body, and what we still don't know.
25 pieces
Rapid weight loss has caused gallstones for as long as people have lost weight rapidly. What these drugs added was the speed, the scale, and a great many people discovering it at once.
Read the pieceRoughly one and a half to two points for semaglutide, and more than two for tirzepatide. The more interesting question is why the number lags a month behind everything you are doing.
The weight that appears in the forties and fifties is not a failure of discipline. It is a redistribution driven by falling oestrogen, and it responds to a different set of interventions than the ones that worked at thirty.
Periods returning, periods changing character, periods arriving on a schedule for the first time in years. It is one of the most commonly reported effects in this drug class and one of the least documented.
The thyroid warning, the pancreatic scare and the colorectal signal are three different arguments with three different evidence bases, and the most consequential finding points the other way entirely.
These drugs are not metabolised by the liver enzymes that cause most interactions, so the usual list is almost empty. What replaces it is a single mechanical problem: everything you swallow now arrives late.
These drugs address the insulin resistance sitting underneath polycystic ovary syndrome, which is why they work. Restoring ovulation in women who believed they could not conceive is the part nobody prepares for.
Wegovy has been licensed for twelve-year-olds since 2022 and the trial data is strong. The disagreement is not really about whether the drug works, which is why it has not resolved.
There are more of these than the two everyone talks about, several are considerably older, and a few are still widely prescribed for reasons that have nothing to do with weight.
Regulators on two continents investigated whether these drugs cause suicidal thoughts and concluded they do not. That finding settles a narrow question and leaves a much larger one open.
The cardiovascular benefit holds in older adults. So does the muscle loss, onto a body that was already losing muscle, in a person for whom a fall is a different event than it was at forty.
Berberine, apple cider vinegar, fibre blends and anything sold as a GLP-1 activator. Some of them do something measurable. None of them does the thing they are being bought for.
It is not a drug side effect. It is the face doing what the face has always done during rapid weight loss, in front of an audience that has never watched it happen this fast or this often.
Almost everyone on this drug class gets abdominal pain at some point. A very small number of them have something that needs an emergency department that evening, and the difference is learnable.
Ozempic, Wegovy and Rybelsus contain the same active ingredient. Almost every argument about which one you should be on is an argument about indications and insurance rather than about chemistry.
Most people sleep better on these drugs within a few months, for reasons that are entirely mechanical. A minority sleep considerably worse first, and almost nobody is warned about the interval.
Every box in this class carries a boxed warning about thyroid tumours in rodents. Fifteen years of human data have not confirmed it, and the warning is still there — for reasons worth understanding.
Eli Lilly added a second hormone receptor to the design, largely as a bet. It produced the largest average weight loss of any approved drug, and nobody can yet fully explain why.
Ozempic and Wegovy contain the same drug. Which one lands in your hand is decided almost entirely by your insurance plan and your diagnosis code — not by your body.
Retatrutide, CagriSema and the triple agonists are aiming at weight reduction that used to require surgery. The interesting question is no longer whether they can get there, but what breaks first.
The mechanism is usually explained either in cartoon form or in a wall of pharmacology. Here is the version in between — enough to reason with, without pretending the picture is complete.
Hair shedding after starting a GLP-1 is real, common enough to be worth naming, and in most cases caused by the speed of the weight loss rather than the drug producing it.
A 2024 study reported a higher rate of a rare optic nerve condition in semaglutide patients. Here is how to read a finding like that without either dismissing it or panicking.
One is a GLP-1 agonist. The other adds GIP. The trial data favor one of them on weight — which is not the same as saying it is the right one for you.
A striking number of people on these drugs report simply losing interest in alcohol. It was nobody's design goal, the mechanism is unresolved, and it may turn out to be one of the most consequential things this class does.
On The Jab
The
GLP‑1
Handbook
Dr. Nick Robertson
MD
The book · 14 chapters
Everything I tell my own patients before their first injection. 214 pages of what actually matters in the first year — dosing, side effects, food, muscle, cost, and the part nobody prepares you for: maintenance.
Priced at four dollars because it should be affordable to everyone taking these drugs — not because it's worth four dollars. No upsell, no course, no supplement line.