Well, they're looking into that. It's likely that the answer is "both," but it's important to note that recent research on weight has shown that weight has a FAR smaller impact on cardiac disease than previously thought, and is in fact mainly a symptom, not a cause, of underlying causes.
Huh! Now THAT is interesting! I recently found out [cardiac disease been my wikipedia rabbit hole for a couple of months] that atherosclerosis only ever happens in arterial blood vessels, not veins - and now what you just said makes me wonder even more about arterial blood chemistry!
Yeah, there's been some really fascinating research on weight, fat, the hormone processes involved, and what it all means for total body health in recent years. There's actually an increasingly-loud call to remove weight as a measure of health entirely, and rely on direct health metrics--
--like blood pressure, lung capacity, A1C, and so forth instead, as they are far better measures of total-body health, are far less likely to cause prejudicial physician interactions ("lose weight and see if that solves it"), and are better at detecting underlying causative health problems.
Maybe my favorite example of all this: Every single world-class powerlifter (and most strength-based athletes generally) are "obese" by traditional weight tracking measures, sometimes "morbidly" so. Which is *ludicrous*.
Yep, I mean that fact alone should be enough to remove body weight as a measure of health not only on an individual level, but even on populations. Everyone has a unique body composition!
Even when people wave that off as "you're not a professional athlete though", they usually shut up when I tell them that at my height and build (5'2, stocky), I would have to have *0% body fat* to have a "healthy" BMI
Put a different way: losing weight has a pretty middling effect on total body health, it's looking like, if the conditions causing weight gain are addressed. Actually, after about 60, carrying extra weight has been found to *extend* life, compared to being at a "normal BMI." (BMI is a junk measure)
I am NOT a medical professional. But I am taking a GLP-1 drug. (Type 1 diabetic, All my fault!) I believe it’s the overall effect. Losing weight Lowering Cholesterol And moving more because you’re no longer lumbering around. I’ve lost over 100 pounds. Life is easier.