Smoking increases the amount of cholesterol and unhealthy fats circulating in the bloods, leading to unhealthy fatty deposits. Over time, cholesterol, fats, and other debris build up on the walls of your arteries. This buildup narrows the arteries and blocks normal blood flow to the heart, brain, and legs. Blocked blood flow to the heart or brain can cause a heart attack or stroke. Blockage in the blood vessels of your legs could result in the amputation of your toes or feet.