Cracking Your Knuckles: Annoying But Doesn't Cause Arthritis

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Should you wait an hour after eating before you jump in the pool? Do you lose most of your body heat through your head? Dr. Aaron Carroll is the co-author of Don't Swallow Your Gum! Myths, Half-Truths, and Outright Lies About Your Body and Health, and he joined Brian Lehrer to take on some of the myths about your health.

Listen to the whole interview:

Do men with big feet have big penises?
No! Despite the role the Hox gene in mammals plays in the development of the toes and fingers as well as the penis or clitoris, there is no correlation between shoe size and penis size according to a survey of 3100 men.

Do fingernails and hair continue to grow after you die?
Despite Johnny Carson's joke, 'For three days after death, hair and fingernails continue to grow, but phone calls taper off,' it is not true. Once you die, your skin dries out and shrinks which can make nails and hair look longer.

Should you poop at least once a day?
No! While pooping regularly does prevent the discomfort of constipation, you're not officially constipated until you have fewer than three stools per week.

Will your hair grow back thicker and darker if you shave it?
No! As early at 1928, a clinical trial demonstrated that shaving had no effect on hair growth and more recent studies have confirmed these findings.