People who are obese are often told to eat healthier and exercise more in order to lose weight. But in an article recently published in The Lancet Diabetes & Endocrinology, obesity experts claim the condition is a chronic disease that can be caused by biological factors, meaning many cases may not be cured with a healthy diet and physical activity alone.

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While a healthy diet and exercise may help obese individuals lose weight in the short term, the experts say around 80-95% eventually gain back that weight.

In the US, around 35% of adults and 17% of children and adolescents are obese. Both the Centers for Disease Control and Prevention (CDC) and the National Institutes of Health (NIH) cite a healthy diet and exercise as a primary factor in combatting obesity. But is it really that simple?

Not according to lead author Dr. Christopher Ochner, assistant professor of pediatrics and psychiatry at the Icahn School of Medicine at Mount Sinai in New York, NY, and colleagues.

In their article, the experts state that while a healthy diet and exercise may help obese individuals lose weight in the short term, around 80-95% eventually gain back that weight.

They explain that this is partly because a reduced intake of calories can activate a type of biological “fat-loss defense” that encourages the body to stay at a higher weight.

According to the authors, this defense mechanism once protected humans when food was scarce. In these modern times, however, humans tend to have higher body weights for longer periods. As such, the defense mechanism drives calorie consumption and fat storage so a higher body weight can be maintained.

The authors say that in a 21st century environment where high-calorie, high-fat foods are the norm, alongside low levels of physical activity, the majority of people who are obese are unable to override the defense mechanism simply through lifestyle changes.

Dr. Ochner adds:

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.

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.”

What is more, Dr. Ochner says that even individuals who were obese and have achieved significant weight loss through dieting may not be able to escape the fat-loss defense mechanism.

“Few individuals ever truly recover from obesity; rather they suffer from ‘obesity in remission,'” he adds. “They are biologically very different from individuals of the same age, sex, and body weight who never had obesity.”

If this is the case, what can obese individuals do to sustain long-term weight loss?

The authors believe the biological mechanisms preventing long-term weight loss need to be addressed going forward.

They note that one form of gastric bypass surgery – known as Roux-en-Y – has been shown to be effective in reversing changes in appetite-related hormones caused by obesity, which affects how the brain responds to food. They say this may be why bariatric surgery appears to be the only obesity treatment that works long term.

In order to tackle obesity, Dr. Ochner says the condition needs to be recognized as a “chronic and often treatment-resistant disease with both biological and behavioral causes,” and it should be treated with biological interventions as well as lifestyle changes.

“Ignoring these biological factors and continuing to rely on behavioral modification will surely result in the continued inability to treat obesity effectively and the premature death of millions of individuals each year,” he adds.

Medical News Today recently learned how a woman became obese after receiving a fecal transplantation from an overweight donor.