Before physiological harm, such as losing your muscles and ultimately your heart muscles, there will be psychological harm, when your hunger prevents you from thinking clearly, so you may become e.g. unable to hold your job.
I am saying this because sometimes "just eat less" is a technically correct answer to losing weight, and yet...
(And the pill breaks the link between the amount of food and how the person feels about it.)
The question rarely asked in modern medicine is why a symptom is present. Doctors and patients almost entirely focus on how to get rid of the symptom, in this case dropping lbs without first understanding why the weight is there.
I equate GLP-1s to simply eating less because my understanding of the mechanism is that is all it does, make a person uninterested, and even in some cases unable, to eat more.
That isn't a moral judgement or a knock against the person, we all have issues we struggle with.
That makes no statement over a measurement of willpower required though, and I don't know of any research linking dietary willpower to genetics. That link could exist, but if it does I don't think we have found it yet and that argument hinges on pharmaceuticals being able to overpower genetics, which is a bold claim.