My heels have been numb for almost a year now. i mostly wear flip flops or no shoes. i also stand for long periods. no pain. why is this?

Many causes: can be result of physical injury to the nerves or a disease condition affecting the nerves. why not get a thorough check up with doc to get to bottom of this, going on long time~ 1 year.

Difficult to tell: Numbness can have many different etiologies. It is difficult to accurately assess your symptoms without doing a proper physical examination. Are you sure the numbness is only in your heels? Do you have other health problems? Your symptoms can be indicative of nerve entrapment or another health malady such as diabetes. See a doctor for a proper assessment.

Flip the Flops.: A reasonable beginning to evaluating your symptoms would be for you to begin wearing appropriate shoes with a cushioned sole and insole. Stop going barefoot and wearing flip flops, as it seems logical that these are the proximate cause, or at least aggravating your condition. After the switch, then reassess your symptoms and then, if no improvement, begin exhaustive neurological studies.