My sister used the shots for about a year, and the doctor she went to absolutely enforced changes in diet and exercise as part of the plan.
In my sister's case, the shot (i don't know if it was glp or one of the others) was a tool. It slowed her digestion to a crawl. She ate very little, and what she did eat, had to be nutrient dense. High protein, healthy fat, decent fiber. The doc made her log her food and exercise and went over it with her each visit. The goal was to get her eating the right things and keeping good habits by the time she was done with the shots. It worked for her.
I think these horror stories about the shots are partially due to doctors who aren't working with the patient to change lifestyle, and are just giving out the meds. that's not gonna work out well. My sister said she had to be really picky about what she did eat, and I'm guessing that these other people were not. If you slow your digestion down and keep eating fried stuff and cheeseburgers, you're gonna wind up exploding your colon.
Could my sister have lost all the weight she did without the shots? maybe. But it sure did kick start the changes she need to make.