Researchers explode widespread myths about obesity
Many people believe that slow weight loss, sex and breastfeeding prevent and relieve obesity. But these are some of the myths which Arne Astrup, DMSc, from the Department of Nutrition, Exercise and Sports at the University of Copenhagen is now laying to rest as part of groundbreaking collaboration with a team of leading American researchers. The goal is to provide more accurate health advice and better policies to combat obesity. The research results are being published today in the New England Journal of Medicine.
An international team of researchers headed by David Allison from the University of Alabama at Birmingham has studied the scientific literature on the subject and compared it with the news coverage in the media with a view to separating the myths from the scientifically documented facts.
The researchers have been able to document that non-scientific opinions about obesity are prevalent globally in everything from slimming guides and TV programmes to social media like Facebook and authorities such as the World Health Organisation and the Danish Health and Medicines Authority. This has a bearing on public health, political decisions and public health recommendations.
“When the Danish Health and Medicines Authority advises overweight people to lose weight by taking small steps towards achieving their goal because, in the long term, it results in greater weight loss, this is a myth which lacks scientific documentation. It shows that even public authorities are contributing to spreading and reinforcing myths in the general population. This problem has to be addressed if we are to stand a chance of battling one of the most prevalent diseases in society,” says Head of Department and Professor Arne Astrup, DMSc, from the Department of Nutrition, Exercise and Sports at the Faculty of Science, University of Copenhagen.
Seven popular myths exposed
The researchers identified seven widely-held myths in the media which fly in the face of the scientific documentation which is available.
“It appears that many people, for example, believe that it is better to lose weight gradually because it helps to prevent us from putting on weight again. However, scientific studies show that the opposite is true – that people who lose weight quickly are better able to maintain their weight level afterwards,” says Arne Astrup, adding:
“You often hear warnings about yo-yo diets or weight cycling, where you ‘cycle’ up and down in weight, as it is supposed to be extremely dangerous. But in the scientific literature there is nothing to say that it is unhealthy; in fact, experiments with animals show that we humans are biologically equipped to tolerate large fluctuations in the size of our fat deposits. A sensible piece of advice would be that you don’t have to worry about putting on weight after you have been on a diet as long as the diet is sufficiently nutritious and is combined with exercise.”
The team of researchers also identified a number of well-documented facts:
“We could, for example, see that when overweight children lose weight, it produces the biggest effect when it takes place at home and involves the child’s parents. Many studies also show that even though being genetically predisposed to obesity plays a role, it is not a decisive factor in whether or not you become obese. Finally, reducing the number of calories you consume is still a safe way of losing weight,” says Arne Astrup.
Regular exercise also proved to help weight loss, but only when you burn more than you consume, which means, of course, that you need to be aware of what you eat.
People hear what they want to hear
According to Dr David Allison, part of the reason why myths have such a big impact is as follows:
“One factor which plays a role is ‘the exposure effect’; if a message is repeated for long enough, people end up believing it. Another contributory factor is our tendency to seek and believe in sources of information which confirm our own views.” The research results are supported by a grant from the National Institutes of Health, USA, and the Nordea Foundation, Denmark. (OPUS-centre)
Read the scientific article "Myths, Presumptions and Facts about Obesity"
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Arne Astrup, DMSc
Department of Nutrition, Exercise and Sports
Faculty of SCIENCE
University of Copenhagen
Mobile +45 2143 3302
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Faculty of SCIENCE
University of Copenhagen
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Myth 1: If you make small and sustained changes to the number of calories you consume or burn, in the long term it leads to large changes in weight.
Fact: Small changes in calorie intake and calorie combustion do not result in big changes. This is because the changes in body mass adapt with time to the small changes in calorie intake and combustion.
Myth 2: It is important to set realistic goals when losing weight because otherwise there is a greater risk that you will give up.
Fact: Incorrect. Several studies document that people lose more weight when they set themselves more ambitious goals.
Myth 3: It is better to lose weight slowly because you are more likely to put it back on after fast weight loss.
Fact: Incorrect. People who lose weight quickly often weigh less – even after several years.
Myth 4: Patients who feel ‘ready’ to lose weight are more willing to make the necessary lifestyle changes – health staff should therefore assess every single patient’s readiness.
Fact: Incorrect. Studies show that measuring a patient’s readiness neither predicts nor aids weight loss.
Myth 5: PE lessons play an important role in relation to reducing and preventing obesity among schoolchildren.
Fact: Incorrect. Ordinary sports education has a lot of health benefits but does not appear to counter obesity. It is possible that it plays a key role when combined with other measures, but there is no scientific evidence to support the claim.
Myth 6: Breastfeeding protects children against obesity later in life.
Fact: Incorrect. Breastfeeding is very beneficial in many ways for both mother and child, but studies in this field do not show it to have any protective effect against obesity.
Myth 7: You can burn up to 300 calories during intercourse.
Facts: The actual number of calories burned during intercourse is closer to a twentieth of this number for an average man i.e. only a little more than the amount of energy used when sitting on the sofa.
The team of researchers behind the results is led by Dr David Allison from the University of Alabama at Birmingham and, in addition to a number of researchers from the University of Alabama at Birmingham, is made up of Head of Department and Professor Arne Astrup, DMSc, from the Department of Nutrition, Exercise and Sports at the University of Copenhagen, Leann Birch from Penn State University, Steven Heymsfield from Pennington Biomedical Research Center, P.K. Newby from Boston University, Kerry McIver and Russell Pate from the University of South Carolina as well as Diana Thomas from Montclair State University.