I'm pretty sure they go into these things with the mentality that "this is a natural substance in the body, surely it can't really be harmful".

Problem is that the body normally produces a reasonable amount of those substances. The body produces a certain amount of it to achieve a balancing act. Insulin to send reasonable amounts of dietary sugar to storage, and GLP-1 to tell your brain that your stomach is full when you've had enough to eat.

When the body requires more and more of those substances that the body produces naturally to control something that should require no more than what the body can produce on it's own, something is wrong - and it's not likely the body's ability to produce proper amounts of that substance. (with the exception of T-1 diabetics who often don't produce any insulin at all)

Increasing dosages of those substances don't really solve the problem at all.

Throwing more and more insulin at high blood sugar instead of addressing the reason for that high blood sugar to begin with is just going to make you more and more insulin resistant, which will require more and more insulin to bring blood sugar down to a proper level after every meal and snack.

Throwing more and more GLP-1 at someone with an uncontrollable appetite isn't going to actually fix the appetite - it just provides enough GLP-1 to diminish appetite while on the drug. But also keep in mind that the GLP-1 drugs are prescribed in a step-up dosage - increasing the dosage each month to the point where you will no doubt eventually become so resistant to the GLP-1 that you have no appetite control at all, or else it controls your appetite to the point that you just don't get hungry at all. Or slows down emptying of the stomach so much that you end up with a blockage and food still in your stomach that you ate weeks earlier. None of those are good results - I mean except for weight loss, which seems to be the ONLY concern.

Just like Insulin, now GLP-1 is being considered a life-time drug. We're just starting to find out the problems that it can cause though - I hate to think what other problems will become apparent over time.

They really need to admit at this point that excessive amounts of carb laden food (even high fiber ones) are the primary cause of these imbalances where you can't keep your blood sugar and/or your appetite and weight under control.