How many people have told you that reading in the dark will cause blindness, snacking is unhealthy and carbs make you gain fat? We are all fooled in one way or another by medical myths that contain false information about how our body reacts to its surroundings and itself.

Here is a list of the most popular myths you might have heard here and there.

  1. The five-second rule. Scientists have put this commonly cited myth to the test numerous times. They’ve found that food that comes into contact with a tile or wood floor does pick up large amounts of bacteria. Food doesn’t pick up many germs when it hits carpet, but it does pick up carpet fuzz.
  2. Cracking knuckles causes arthritis. Studies show that people that crack their knuckles are no more likely to have arthritis than those who don’t make annoying popping sounds with their fingers. Happy cracking everyone!
  3. Cold weather causes colds. In studies of cold transmission, people who are chilled are no more likely to get sick than those who are not. Cold weather does not compromise your immune system. It may be, however, that cold weather keeps people indoors, where germs are more likely to catch up with you.
  4. Yawning makes you even sleepier. While people commonly misperceive yawning as being caused by lack of sleep, yawning increases alertness as people exhale more oxygen and get more blood flowing to their brains.
  5. Startling yourself helps to get rid of hiccups. Hiccups are simply spasms of the diaphragm; your diaphragm muscles and controlling nerves get stuck in a “reflex arc,” where the nerves keep signaling the diaphragm to contract suddenly, causing your hiccup. Startling someone is a common misconception to treat hiccups, as it attempts to stretch the diaphragm, but that does not actually happen from sudden bursts of surprise.
  6. Eating standing up helps burn off the calories. Studies show that standing burns 40 percent more calories than sitting. Over time it might give you an advantage, but the bigger problem is that people tend to eat differently when they are standing: We often don’t pay as much attention to what or how much we’re eating and end up making less-healthy choices and consume more.
  7. Reading in the dark will hurt your eyes and cause blindness. “Since the pupils of your open wider in dim light, that makes it more difficult to focus on fine detail, such as reading,” says Jeffrey Anshel, O.D., fellow of the American Academy of Optometry and president of the Ocular Nutrition Society, but that doesn’t damage your retina. If reading in dim light was harmful, our ancestors who read by candle light would have all been blind.
  8. Swimming after eating causes cramps. After eating, your blood flows to your digestive system and causes you to have less energy but it does not necessarily cause cramps; that is a direct result of lack of oxygen.
  9. Carrots improve your vision. The photoreceptors in our retina do not work well because of the vitamin A (beta-carotene) found in carrots; instead, carrots prevent degeneration of the eye after age 16. So keep eating them folks, but don’t take off your glasses.
  10. Eggs are bad for your heart because of its high cholesterol count. Many studies now show that your body counteracts the small amount of cholesterol in eggs using homeostasis (self-balance and regulation) and produces less cholesterol. Studies also show that one egg a day is not unhealthy and is actually recommended by many doctors due to their high protein content.  
  11. Fasting from food removes toxins. Removing toxins is a function only of a healthy liver and healthy kidneys, as your body produces its own toxins as well.
  12. Microwaves cause cancer. Examples of high-energy radiation include x-rays and gamma rays. They, as well as some high-energy UV radiation, are called ionizing radiation, which means they have enough energy to remove an electron from an atom or molecule, which is called ionization. This can damage the DNA inside of cells, which can result in cancer. Radiofrequency (RF) radiation, which can be found in radio waves and microwaves, is at the low-energy end of the electromagnetic spectrum. It is a type of non-ionizing radiation. Non-ionizing radiation has enough energy to move atoms in a molecule around or cause them to vibrate but not enough to ionize an atom or molecule (remove charged particles such as electrons). That’s why the food is hot.
  13. Muscles turn to fat when you don’t exercise. Before gaining weight, you will actually temporarily lose weight because of a loss of muscle, and only then will you begin to gain fat weight. However, they don’t convert into each other, so only your fat weight will increase from a lack of exercise (given that all other factors of weight increase, such as a rise in caloric intake, are controlled).