Wellness for Life Blog | Can Collagen Cause Weight Gain explains the truth about collagen supplements. Collagen itself does not directly cause weight gain. It is a natural protein that supports skin, joints, and muscles. Some people may notice changes in appetite or muscle mass, but these are not the same as gaining fat. Always follow recommended usage and ask your doctor for advice. https://camp-fire.jp/profile/Wellnessforlifeblog/projects