31 January 2013

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.

Arne Astrup

Centre Director of OPUS, professor Arne Astrup. Download free press photo.

There are many ideas circulating on which measures are required to prevent and treat obesity.

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"


Centre Director for OPUS, Arne Astrup mobile +45 2143 3302  or email ast@nexs.ku.dk