Red flag: Numbness in both feet

What it means: Being unable to "feel" your feet or having a heavy pins-and-needles sensation is a hallmark of peripheral neuropathy, or damage to the peripheral nervous system. That's the body's way of transmitting information from the brain and spinal cord to the entire rest of the body. Peripheral neuropathy has many causes, but the top two are diabetes and alcohol abuse (current or past). Chemotherapy is another common cause.

More clues: The tingling or burning can also appear in hands and may gradually spread up to arms and legs. The reduced sensation may make it feel like you're constantly wearing heavy socks or gloves.

What to do: See a physician to try to pinpoint the cause (especially if alcohol addiction doesn't apply). There's no cure for peripheral neuropathy, but medications from pain relievers to antidepressants can treat symptoms.