Diet and exercise alone won't lead to sustained weight loss, say experts
A leading group of obesity experts writing in The Lancet question the value of current obesity treatments
Forget spinning classes and salads. Diet and exercise are often prescribed for the obese, but these do nothing for lasting weight loss, argue a group of obesity experts in a commentary published online in a leading journal today.
Writing in The Lancet Diabetes & Endorcrinology, lead author Dr Christopher Ochner, the assistant professor of paediatrics and psychiatry at the Icahn School of Medicine at Mount Sinai in New York, says “the mere recommendation to avoid calorically dense foods might be no more effective for the typical patient seeking weight reduction than would be a recommendation to avoid sharp objects for someone bleeding profusely.”
Ochner and colleagues argue that obesity is a chronic, and often treatment-resistant, medical disease with biological and behavioural causes that cannot be cured with just eating less and moving more.
Many obese people are able to lose weight for a few months, but the majority regain their lost weight eventually because of biological adaptations, the experts say.
The first kind of biological adaptation prevents starvation, and evolved when humans needed to survive times of food scarcity. The authors suggest that caloric restriction actually triggers several biological systems that drive us to eat high-calorie foods and gain weight.
The development of obesity also causes additional biological adaptations that encourage calorie consumption and storage of fat, the authors say, and these function to preserve – or even increase – a person’s highest sustained lifetime bodyweight.
“Importantly, these latter adaptations are not typically observed in individuals who are overweight, but occur only after obesity has been maintained for some time,” the authors say.
“Thus, improved lifestyle choices might be sufficient for lasting reductions in bodyweight prior to sustained obesity. Once obesity is established, however, bodyweight seems to become biologically stamped in and defended.”
Ochner and colleagues point out that recent evidence suggests these biological adaptations often persist indefinitely, even when a formerly obese person regains a healthy Body Mass Index via diet and/or exercise. Further evidence, they say, shows that as weight loss increases, so does one’s biological pressure to restore bodyweight to the highest-sustained lifetime level.
The authors suggest that few obese people ever truly recover from the condition; rather those who re-attain a healthy bodyweight via diet and exercise still have “obesity in remission”. “Such people are biologically very different from individuals of the same age, sex, and bodyweight who never had obesity,” say the experts.
For sustained weight loss, the authors argue that more biologically-based interventions are needed. However, they note that current biologically-based treatments are limited to anti-obesity drugs, weight-loss surgery and intra-abdominal vagal nerve blockage, which do not permanently correct the biological factors that undermine weight-loss effort.
Bariatric surgery – in particular Roux-en-Y gastric bypass – is the only available treatment to show long-term effectiveness, say the authors. Sustained weight-loss of roughly 25 per cent of initial bodyweight has been reported up to 20 years following the surgical procedure.
To conclude, the authors recommend the use of lifestyle modifications to treat people with sustained obesity, but it should be only one component of a multimodal treatment strategy that includes medication or surgery when appropriate.
According to a comprehensive analysis of overweight and obesity worldwide published in The Lancet last year, 36.9 per cent of adult men and 38 per cent of adult women had a Body Mass Index of 25 or greater (indicating overweight) in 2013. This is significantly higher than in 1980, when it was 28.8 per cent for men and 29.8 per cent for women.
Prevalence has also increased substantially in children and adolescents in developed countries; 23.8 per cent of boys and 22.6 per cent of girls were overweight or obese in 2013.
In 2010, overweight and obesity were estimated to cause 3.4 million deaths.