Plump, soft arms can be the bane of teenage girls that want to wear sleeveless tops and bathing suits. The cause of plump arms is often a combination of poor eating habits and lack of upper arm musculature. To slim down your arms and give them a nice shape, follow a program of healthy eating and targeted exercise.
Improve your diet so you can lose weight and reduce fat. Limit or eliminate the amount of simple sugars and carbohydrates you consume. Substitute raw vegetables, popcorn, nuts and fruits for fatty snacks. Add more lean proteins such as seafood, tofu, beans and chicken to your meals.
Increase your cardiovascular activities to burn calories and reduce body fat so the muscles in your arms are visible. Join a sports team or take up an activity such as dancing or gymnastics. Jump rope or jog in place if you can't leave home. Walk or run to places that you would normally reach by transportation. Aim for at least 30 minutes of cardio every day.
Build up the muscles in your arms to give them shape and to burn calories even when you're resting. Use dumbbells or makeshift weights such as soup cans or water bottles to add resistance to exercises. Do overhead presses for your shoulders. Do bicep curls for the front of your arms and triceps extensions for the back. Work several arm muscles at once by performing push-ups.