Speed up your slim down with Ryn Footwear. Though they're light as a feather (goodbye, joint stress!), these sneaks deliver the ultimate workout while making your body feel all-around healthier. Thanks to the one-two punch of a 7-layer midsole/outsole design and an encapsulated air tunnel in the heel, these calorie-burning kicks will stimulate sleepy muscles, tighten your tush, and perk up your posture. Hailing from Korea, (where they're a bestseller), they've been getting raves stateside, even from the FDA, who has approved them as a medical device. (Impressive, we know.) Wear a pair and see for yourself: lightweight footwear that packs a heavyweight punch against those extra pounds.