Encouraging people to improve their diet and exercise more may not be enough to overcome the obesity epidemic, according to several new research papers.

Writing in The Lancet, obesity experts behind the paper Treating obesity seriously: when recommendations for lifestyle change confront biological adaptations, have suggested that obesity is a chronic disease with largely biological causes that cannot be cured with just diet and exercise.

Although better diet and increased exercise do help people to lose weight, a reported 80-95 per cent of these regain their lost weight eventually. The authors posit that reducing calorie intake triggers biological systems that drive us to eat high-calorie foods and gain weight – an evolution legacy from when humans had to contend with periods of food scarcity. But in modern humans, who have been obese for an extended period of time, this ‘fat defence’ leads the body to yearn for a return to an individual's highest sustained weight.

"Although lifestyle modifications may result in lasting weight loss in individuals who are overweight, in those with chronic obesity, body weight seems to become biologically 'stamped in' and defended," said Dr Christopher Ochner, lead author and Assistant Professor of Pediatrics and Psychiatry at the Icahn School of Medicine at Mount Sinai in New York, USA.

"Therefore, the current advice to eat less and exercise more may be no more effective for most individuals with obesity than a recommendation to avoid sharp objects for someone bleeding profusely."

Meanwhile, for another paper published in the journal Nature, researchers from the international Giant consortium (Genetic Investigation of Anthropometric Trait) have found results that suggest neurological factors may play a role in obesity.

The scientists have created what is reportedly the largest-ever genetic map of obesity, built by examining the DNA libraries of more than 300,000 people.

They uncovered more than 90 new gene regions and say these may help to shed light on why some people are more likely to put on weight than others. Although it’s not fully clear what role each genetic region plays in obesity, researchers believe that some genes contribute to how we control our appetites, while others are linked to memories and attitudes towards food.

Experts say the findings could help to understand the more complex contributory factors towards obesity, in turn leading to more informed strategies to prevent it.

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