can collagen peptides cause weight gain?

Adding to what Emma and the Noah said—the collagen doesn’t cause weight gain, but the delivery system might!
If a brand wants us to manufacture collagen gummies or heavily flavored RTD (ready-to-drink) beverages, we often have to use cane sugar, syrups, or artificial flavorings to mask certain notes. Those added sugars and extra calories are what cause weight gain. If a brand wants a “clean label” product that won’t affect weight, I always advise them to stick to unflavored, easily dissolvable powder blends.