GLP-1s have been used for over 20 years. There likely is enough data to say something, even if it's not water tight.

They've been used for over 20 years but until they became a weight loss drug recently, almost all of the research was on diabetics which introduces two confounding factors: diabetes and the diets diabetics already have to follow to manage the disease. It's hard to draw any conclusions when the results are muddied by those two factors.