When you wear heels, your body weight shifts toward the balls of your feet, or the metatarsals. “This creates a misalignment of the entire skeleton,” says Sutera. “When weight gets shifted forward, the knees and hips go forward, as well, and the back has to hyperextend.” This effect not only causes short-term issues like blisters, shin splints, and sore muscles from the feet to the back, but it can also strain Achilles tendons and worsen bunions and hammertoes. Pinched nerves, stress fractures, arthritis, and nail problems are also long-term side effects.