Ladies: There's No Evidence That Men With Big Feet Have Bigger Penises. Sex Myths And The Scientific Truth Behind Them.

Most of us have learned all sorts of things about sex - from talking to friends, sex education at school, the TV or the internet. Some things you might even have figured out from experience. But while you may have plenty of information, some of it is plain wrong. In fact, people believe all kinds of things about sex that are simply not true. 

Here are the most popular and prevalent sex myths and the scientific truth behind them. 

• 1. BIG FEET, BIG... AHEM!  

 Many people think you can size up what a man's penis is like by looking at his feet, hands, or nose. Truth is there's no good evidence that men with big feet have bigger penises.  You can look at a man's feet all you want, but it's only going to give you an idea about his taste in shoes. 

• 2. MEN THINK ABOUT SEX EVERY 7 SECONDS

You probably believe men think about sex every seven seconds. But that would mean men are thinking about sex more than 6,000 times a day, or pretty much every time they take a breath. That would not only drive most people mad, it would make them incapable of performing any other functions at all.  

However, it's true research data suggests men think about sex more than women do, but the difference is far less dramatic than you might think. Almost half of men don't think about sex every day - and that's  a far cry from the way they are frequently portrayed. 

• 3. SEX HELPS YOU LOSE WEIGHT

Sounds plausible, doesn't it? But unless you are having sex for much longer and with much more vigour than the average person, sex is probably not going to get you anywhere near the recommended amount of exercise to lose weight.  

Sex is considered to be only a mild to moderate intensity activity, and the average sexual encounter lasts only around five minutes. Estimates of how many calories are used up range from 25 to 125 - not a great deal.   

• 4. SEX IS BAD FOR A DODGY TICKER 

Everyone has heard horror stories of people dying of a heart attack in the middle of sex, and those with a history of heart disease may be particularly afraid that sex is too much for their heart. But the chance of having a heart attack during sex is very low.  

A large study called the Framingham Heart Study tells us that if you are a man who doesn't have diabetes and doesn't smoke, the chance is just one in a million. And while people who've had a heart attack do need to exercise some caution when resuming normal activities, they do not need to be so afraid of having sex.  

The truth is that most people just don't exert themselves that much during sex. The physical exertion is similar to walking up two flights of stairs. So if you can do the treadmill test (the stress test used to check heart function), this is about the same level of exertion you'd have during sex that produces an orgasm.   

• 5. THE PILL WILL MAKE YOU FAT  

Nearly all medications have side-effects. But it is a myth that the Pill causes weight gain. It wasn't always the case - when it was first developed, the Pill had very high levels of oestrogen and progestin - a synthetic version of the hormone progersterone - which might have caused weight gain. But today's Pill contains much lower levels of hormones,  and two major reviews of all the studies found no evidence of weight gain. 

• 6. TESTICLES SAG WITH AGE  

Most men think so. And the male reproductive tract definitely goes through a number of changes with age - the testicles produce fewer sperm, slower sperm, and sperm that are less able to fertilise an egg. The components of the testicles also start to change. The tiny tubes where sperm are produced start to degenerate, and, overall, testicles also become smaller. These smaller testicles may seem to be hanging lower, but this is because the sac is a bit emptier. 

But while it's true there might be some weakening of the skin of the scrotal sac, the smooth muscle that controls the movement of the scrotal sac up and down continues to function for life. And that kind of muscle - smooth muscle- is unlikely to sag very much. 

• 7. SEX BEFORE SPORT IS BAD 

Many athletes are told they should not have sex the night before a big game because they will have less strength, less concentration, or not enough testosterone to fuel an aggressive, strong performance.  

In fact, the science of what happens in the body during and after sex suggests athletes might actually perform better if they did have sex. In one study, men who had sex the night before a sporting event had higher testosterone levels the next day than those who had not had sex.  

Sex has also been shown to have no impact on leg muscle strength, grip strength, reaction time or flexibility.