When it comes to sex, everyone has a theory.

We have all heard theories about different ways to spice up your sex life, food that gets you in the mood, and even pills that will enhance performance.

Yet, there is one theory that has been consistently unanimous when it comes to sex; that size matters a lot. Particularly when it comes to weight!

Can a partner's weight enhance or diminish the pleasure between the sheets? Some people have radical theories about weight and sex. Some claim they prefer cuddly partners while some swear by the "slender never gets tired" phrase.

But how true are the theories? What is a myth and what is fact when it comes to weight and sex?

Sex therapist Dr Marelise Swart and author Mofenyi Malepe weigh in on this debate. Swart starts off by saying that the shape of your partner is all a matter of preference.

"Some people have a fetish for overweight people, as they prefer to have something to hold on to, whereas some people are put off by excessive weight in the bedroom," she says.

Malepe, on the other hand, says one's weight would only be a factor in the bedroom if certain positions are difficult to do.

"It all depends on the position the couple chooses to try. A typical example: I cannot place an overweight woman on the bonnet of the car if we wanted [to do] it there or on a kitchen counter if the counter stands on weak legs. So positions can be limited in that regard," he says.

Swart agrees that some positions may not be possible because of excess weight. "You cannot swing on chandeliers, for example. Having said that, I know couples who have very active sex lives despite having a bit of meat on their bones. It depends on what sex positions you are comfortable with."

We break down some of the myths surrounding weight and sex, and put them to our sex panel.

1. Some men claim that curvier women are better in bed.

Swart says: Myth.

"There is no basis to say that big women are better or worst in bed. It is all a matter of perspective."

Malepe says: Fact.

"Having been with women of all shapes and sizes, I'd say meatier women are [greater in bed]."

2. Big men have a smaller penis.

Malepe: Myth.

"I know fat guys who are average-sized, and some who are very well-endowed. Big-bellied guys are mostly perceived to be tiny because the excessive fat becomes a disturbance during sex . But take the belly out of the equation and you are bound to find a guy with a competitive tool."

Dr Swart: Myth.

"It's an illusion. The man's weight can swallow up his penis, making it appear smaller, but it doesn't mean that all big men are small."

3. Tall, skinny guys are very well-endowed.

Dr Swart: Myth.

"Skinny guys may appear to have larger members because there is nothing being obtrusive in their genital areas like excessive weight. So because they show up in all their glory, this may form the misconception that thin guys are more well-endowed. It is in no way true."

Malepe: Myth

"I know some skinny and tall guys who walk around with small tools. It is a total myth."

4. Two big people can't enjoy sex.

Malepe: Fact.

"Excess weight is a disturbance in itself . you cannot do most things in life without being reminded by resistance of your own body. Now imagine when you want to do bedroom aerobics and you are always compelled to find sex positions that are suitable for both of you. It becomes a chore after a while."