The mantra in obesity treatment and weight-loss counseling has long been ‘eat less and move more‘. But a leading group of obesity experts writing in The Lancet Diabetes & Endocrinology journal call into question the belief that this is sufficient to treat obesity. They argue that obesity is a chronic disease with largely biological causes that cannot be cured with diet and exercise alone.
Many people with obesity can lose weight for a few months, say the authors, but 80 to 95 percent regain their lost weight eventually. One explanation for this limited long-term success is that reducing caloric intake triggers several biological systems that drive us to eat high-calorie foods and gain weight. For instance, recent research has uncovered molecular responses to obesity that trigger abnormalities in the hormone leptin, which regulates appetite.
These biological systems evolved when humans needed to survive times of food scarcity. But in modern humans who have had obesity for some time, these biological adaptations encourage calorie consumption and the storage of fat to protect an individual’s highest sustained weight — in other words, after a person becomes obese, their body will fight to keep them that way.
Bodyweight seems to become biologically ‘stamped in’
Overriding this fat-loss defense does not appear possible for most individuals through just lifestyle changes, say the authors, particularly in a 21st century environment that promotes the consumption of calorie-dense, high-fat foods along with low energy expenditure.
“Although lifestyle modifications may result in lasting weight loss in individuals who are overweight, in those with chronic obesity, bodyweight seems to become biologically ‘stamped in’ and defended,” explains Dr. Christopher Ochner, lead author of the article and Assistant Professor of Pediatrics and Psychiatry at the Icahn School of Medicine at Mount Sinai in New York.
“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,” says Dr. Ochner.
Moreover, he point outs, recent evidence suggests that these biological adaptations could persist indefinitely, even in formerly obese individuals who achieve a healthy bodyweight through dieting. “Few individuals ever truly recover from obesity; rather they suffer from ‘obesity in remission’. They are biologically very different from individuals of the same age, sex, and bodyweight who never had obesity.”
Biological causes of obesity must be incorporated into treatment
The authors argue that if weight loss is to be sustained in the long-term, at least some of these biological factors need to be addressed. However, current biologically based treatments, such as antiobesity drugs and weight-loss surgery, are expensive and do not permanently correct the biological factors that undermine weight-loss. To date, only gastric bypass, a common surgical procedure for extreme obesity, has been shown to reverse obesity-induced changes in appetite hormones and the brain’s response to food. This, the authors say, might explain why bariatric surgery is the only treatment showing long-term effectiveness in individuals with sustained obesity.
According to the Centers for Disease Control and Prevention, more than one-third of American adults are obese — defined as having a body mass index of 30 or higher — and about 6 to 7 percent are extremely obese, with a BMI or 40 or above. Obesity is one of the leading causes of morbidity and mortality worldwide, increasing the risk of conditions such as heart disease, stroke, type 2 diabetes and certain types of cancer.
The authors recommend that obesity should be recognized as a “chronic and often treatment-resistant disease” with both biological and behavioral causes. As such, clinicians working with obese patients should consider a range of medical interventions, including biologically based interventions — such as pharmacotherapy or surgery — as well as lifestyle modification.
“Ignoring the 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,” adds Dr. Ochner.