Influence of 'obesity gene' can be offset by healthy diet

Children who carry a gene strongly associated with obesity could offset its effect by eating a low energy density diet, according to new research from UCL (University College London) and the University of Bristol published today in PLoS ONE.

The study, based on data from a sample of 2275 children from the Bristol-based ALSPAC study (Children of the 90s) provides evidence that people might be able to avoid becoming obese if they adopt a healthier diet with a low energy density – even those who carry the FTO gene, identified as being a high risk gene for obesity.

Dietary energy density (DED) refers to the amount of energy consumed per unit weight of food, or number of calories per bite. A low dietary energy density can be achieved by eating lots of water-rich foods like fruits and vegetables and limiting foods high in fat and sugar like chocolate and biscuits.

The researchers looked at how DED affected the build up of fat in the body over a period of three years in children aged between 10 and 13 years old. They found that children with a more energy dense diet (more calories per bite) tended to have more fat mass three years later and also confirmed that those carrying the high risk gene had greater fat mass overall.

When the researchers looked at whether children with the FTO gene had a stronger reaction to an energy dense diet than children with a lower genetic risk they found that they did not. These results indicate that if a child with a high genetic risk eats a diet with fewer calories per bite, they may be able to offset the effect of the gene on weight gain and so stay a healthy weight.

Lead author Dr Laura Johnson, UCL Epidemiology and Public Health, said: "This is an important finding because it provides evidence that it's easier to eat too much energy and gain weight when your diet is packed tight with calories, so adopting a diet with more bulk and less energy per bite could help people avoid becoming obese regardless of their genetic risk. Obesity is not inevitable if your genes give you a higher risk because if you change the types of foods you eat this will help curb excessive weight gain."

"This shows that although our genetic make-up does have an influence on our health, it's certainly not the only defining factor. Those with high risk genes can, in some cases, resist their genetic lot if they alter their lifestyle in the right way – in this case, their diet."

FTO is the first common obesity gene to be identified in Caucasian populations. Previous studies have shown that adults with two copies of the FTO gene are on average 3kg heavier, and individuals with a single copy are on average 1.5kg heavier, than those without the gene.

1. For more information, or to interview the researchers quoted, please contact Ruth Metcalfe in the UCL Media Relations Office on tel: +44 (0)20 7679 9739, mobile: +44 (0)7990 675 947, out of hours +44 (0)7917 271 364, e-mail: r.metcalfe@ucl.ac.uk

2. The paper "Dietary energy density affects fat mass in early adolescence and is not modified by FTO variants" is published online ahead of print in PLoS One. For copies of the paper, please contact UCL Media Relations.

3. The data was taken from the Avon Longitudinal Study of Parents and Children (ALSPAC) and analysis was carried out by researchers at UCL, Bristol University, Peninsula Medical School, and MRC Human Nutrition Research in Cambridge.

4. ALSPAC (also known as Children of the 90s) is a unique ongoing research project based in the University of Bristol. It enrolled 14,000 mothers during pregnancy in 1991-2 and has followed most of the children and parents in minute detail ever since. The ALSPAC study could not have been undertaken without the continuing financial support of the Medical Research Council, the Wellcome Trust, and the University of Bristol among many others.

Founded in 1826, UCL was the first English university established after Oxford and Cambridge, the first to admit students regardless of race, class, religion or gender, and the first to provide systematic teaching of law, architecture and medicine. UCL is the seventh-ranked university in the 2008 THES-QS World University Rankings, and the third-ranked UK university in the 2008 league table of the top 500 world universities produced by the Shanghai Jiao Tong University. UCL alumni include Marie Stopes, Jonathan Dimbleby, Lord Woolf, Alexander Graham Bell, and members of the band Coldplay. UCL currently has over 12,000 undergraduate and 8,000 postgraduate students. Its annual income is over £600 million.