Dumbbell swings or kettlebell swings are great for fatloss, core stability and strength. Both are a posterior chain exercise that primarily work the glutes (butt) and hamstrings (back of the thighs), as well as the TVA (deep lower abs).
You should be doing virtually no work with the front of the shoulder or quads (front of thighs) so if you feel the front of your legs or front of the shoulders working that means you're not generating power from the core and hips to perform this exercise and this will result in injuries so please be sure to draw in those lower abs and drive the hips forward by squeezing the butt as you swing up.
When doing this exercise properly you will feel your deep abdominal muscles working hard and arms will feel like they're just along for the ride.
Once you start to swing the weight higher be sure to keep those shoulder blades locked down (shoulders away from ears).
You can perform this exercise with kettlebells, sandbells, and clubbells. You also can perform other versions including 2 arms 1 weight, 2 arms 2 weights, and alternating arms. If you're new to this exercise the 2 arm one weight version is the one to learn first.
Below are videos of the one arm dumbbell swing and the 2 clubbell swing. You can also watch me doing swings with the sandbell in the Gymboss Tabata Intervals Workout video.