The best walking posture is to stand up straight, not leaning forward or back. Shrug your shoulders and let them fall and relax. Suck in your stomach slightly and slightly tilt your pelvis forward so you are not arching your back too much. With the right posture not only will you walk easier and be able to walk faster if you wish, you will also look thinner. Some racewalking coaches in past decades recommended a slight forward lean, but it proved not to provide any advantage.
How to Walk: Posture
Looking Thinner and Walking Great

Next Question -->