@the_modernsapien: Loose skin after major weight loss is different from body fat. Building muscle can improve the look by adding shape underneath the skin, but how much loose skin remains depends on things like how much weight you lost, your age, and genetics. If you’re lifting but seeing no change, make sure you’re actually progressing. Get stronger over time. Eat enough protein. Stay consistent long enough to build muscle. You may not be able to completely eliminate loose skin with exercise, but you can absolutely improve how your arms look.