Collecting this in one place because it comes up every few weeks and the answer is always assembled from scratch. It is about cardiovascular outcomes, and it is deliberately narrow — everything I am not confident about is marked as such.
What is actually established
SELECT is the trial that changed the framing of this class, because it was an outcome trial rather than a weight trial: about a 20% relative reduction in major adverse cardiovascular events in people with established cardiovascular disease and overweight or obesity, without diabetes. The effect appeared earlier than the weight-loss curve can comfortably explain, which is the basis for arguing that some of the benefit is direct — anti-inflammatory and vascular — rather than purely a consequence of weight.
The condition it depends on
The qualification that SELECT enrolled a secondary-prevention population. Extrapolating a 20% relative reduction to a healthy 35-year-old with a BMI of 31 is not what that trial showed.
The practical version
Relative versus absolute is the distinction that gets lost: a 20% relative reduction on a high baseline risk is a large absolute benefit, and the same relative figure on a low baseline risk is a small one.
What I am not sure about
The narrow version of the question is how much of the SELECT benefit is plausibly independent of the weight loss, and whether that distinction changes anything practical. I have searched first, so if this is covered somewhere point me at it and I will read it.
— cory_ATX · corrections welcome and will be edited into this post with credit