A romp between the sheets burns a lot of calories, right? Not the way we have sex, say researchers of a recent study in which common assumptions about weight and health were dispelled as being little more than old wives tales.
Beliefs that sex burns calories or that skipping breakfast is bad can be downright wrong, according to the research published in the New England Journal of Medicine, and could even be fuelling the obesity crisis faced by many nations.
"The evidence is what matters," explains lead author, David Allison, a biostatistician at the University of Alabama at Birmingham, and the problem with these widely-assumed beliefs is that they lack any strong supporting evidence.
The researchers set about evaluating the science behind popular beliefs surrounding obesity by sifting through previous related research.
The belief that sex is a good way to burn calories is one such assumption. While claims suggest that a romp in the sack might help you burn between 100 to 300 calories, the only supporting evidence that the researchers we able to find was an experiment done in 1984 which measured the energy output of sex. The result showed that the average sex session lasts a disappointing six minutes and that men typically burned just 21 calories – the equivalent of walking. The experiment didn't measure the experience for women.
More popular beliefs that Allison and his team analysed were the following:
Myth: If you snack often you'll pick up weight.
Truth: According to the authors there are no studies offering strong evidence to back this up.
Myth: Losing weight slowly over a longer period of time is better than dropping weight quickly.
Truth: Researchers found that many people who lose weight (whether slowly or quickly) tend to regain some of this weight. However, those who lost weight quickly tend to remain at a lower weight than those who lose weight more slowly.
Myth: Physical education classes in school helps keep children fit.
Truth: In truth, these classes are neither long enough nor frequent enough to have any lasting impact on children's health.
Myth: Eating breakfast every morning helps thwart obesity.
Truth: Two studies analysed by the researchers showed eating breakfast had no effect on weight.
Myth: Setting overly-ambitious weight-loss goals can only results in frustration and losing less weight. Truth: Some people do very well when challenged by ambitious weight-loss goals, according to some studies.
Myth: Making small changes in your exercise routine or eating plan can lead to big, long-lasting weight changes.
Truth: Our bodies adapt to change easily, meaning that small calorie-cutting changes won’t have the same initial effect as time goes on.
Independent researcher Marion Nestle, a New York University professor of nutrition, says that while this research paper dispels some harmful and useless myths about health and diet, there is cause to question the researchers' motives. All the researchers have interests in weight loss products disclosed in the paper.
"It raises questions about what the purpose of this paper is," she observes, suggesting that the paper's conclusion - that weight loss supplements are effective against obesity - is questionable.
"The big issues in weight loss are how you change the food environment in order for people to make healthy choices," adds Nestle.