Health urban legends float around on the internet like a ghost who doesn't seem to go away. But which ones should you believe?

Prevention magazine lists down some of the craziest health rumours. Here are five of them:

Does exercising on an empty stomach burn more fat?                                                                   Prevention magazine says that it is possible, but overall fat burn wil be minimal. During exercise, the body burns both fat and carbohydrates for calories. Studies have shown that working out without eating might burn a few more calories. However, the total amount of calories expended is still about the same, continued the Prevention report.

Can eating too much sugar cause diabetes?
Sugar may play a part in triggering the condition, says Prevention magazine. For starters, a hefty intake of sugar can cause weight gain and being overweight increases one's risk of developing Type 2 diabetes.

However the magazine points out also that new research has established that eating too much sugar can increase risk regardless of weight.

Are dental fillings that contain mercury dangerous?
Probably not, says Prevention magazine's advisor Andrew Weil, MD.

Some critics claim that amalgam fillings may lead to health problems such as Alzheimer's as they release minute amounts of mecury when they are placed in or removed from teeth, and when a person chews. However, almost every major health organization in America has declared such fillings safe, notes Prevention magazine. Two extended studies of about 500 children each who had amalgam fillings found no significant changes in IQ, attention span and memory.

Can thong underwear cause infections down there?
Prevention magazine's advisor, Dr Mary Jane Minkin says that she has not received any complaints from her patients who wear g-string underwear. However she says that it may be theoretically possible for infections to occur. The thin sliver of cloth that is at the back of the thong usually rests on the anus and has a direct line to the vagina or urinary tract. This makes it possible for fecal bacteria to infect the private parts. A thong can also create tiny cracks in the skin between the anus and the vagina, leading to mild irritation.

Here's the good news: if your g-string does not bother you, there's no medical reason to stop wearing it, says Prevention magazine.

Will eating after 9pm cause weight gain?
Most people think that metabolism slows down at night, but that is not true. Eating at night may cause you to gain weight if you consume more calories than what your body usually expends. Many people practise emotional eating at night - out of boredom or otherwise - and they end up consuming more calories than is needed for the day. The extra calories are stored as fat.