Obesity Is a Disease, Not a Choice, Experts Advise

Pam Harrison

May 09, 2018

TORONTO — Effective weight management is going to require a paradigm shift in they way healthcare professionals think about obesity, a leading expert in the field suggests.

Otherwise, patients are doomed to failure and blame, despite the fact the medical community should be shouldering some of the responsibility for not having developed more effective interventions, said Lee Kaplan, MD, PhD, director of the Obesity, Metabolism and Nutrition Institute at Massachusetts General Hospital in Boston.

"My colleagues and I believe — and the Obesity Society and other professional organizations agree — that obesity is a disease," Kaplan told delegates here at the Pediatric Academic Societies 2018 meeting.

As such, obesity must be driven by pathophysiologic processes, just like type 2 diabetes and other chronic diseases, stressed Kaplan.

Like diabetes, obesity is also never "cured," although a patient's body mass index (BMI) can be under excellent control. Patients "still have the disease of obesity, even though they no longer meet the definition of obesity by our measurements," Kaplan explained.

If obesity is, in fact, a chronic disease, then physicians need to treat it as a chronic disease. And there are many good reasons to do so, he pointed out. First, obesity carries substantial adverse health risks. Type 2 diabetes, for example, is common in the setting of obesity, as are hypertension, dyslipidemia, sleep apnea, and fatty liver disease.

People on the Mediterranean diet did better in terms of cardiovascular risk reduction if they had obesity, but they did so despite an average weight loss of less than one pound.

Common treatable comorbidities typically dictate the treatment that patients with obesity receive, but treatment for obesity itself is often overlooked. In addition, treatments known to improve the comorbidities of obesity are often incorrectly assumed to help obesity itself. A salient example is the oft-recommended Mediterranean diet to promote weight loss in patients with obesity.

Results from several large trials have shown that the Mediterranean diet has little effect on body weight, despite frequent claims to the contrary. In one landmark study (N Engl J Med. 2013;368:1279-1290), people who followed the Mediterranean diet reduced their risk for cardiovascular disease significantly, but the diet had no appreciable effect on body weight.

"People on the Mediterranean diet did better in terms of cardiovascular risk reduction if they had obesity, but they did so despite an average weight loss of less than one pound," Kaplan pointed out.

"We have to be careful about what we tell our patients because if we tell them they are going to lose weight or prevent weight gain on a particular diet and it doesn't work out, then patients and parents themselves will say, 'they don't know what they are talking about' and give up," he said.

Paradigm Shift

Perhaps the most powerful argument for shifting away from thinking that obesity is a lifestyle choice comes from a global study in which researchers tracked trends in BMI from 1980 to 2013 (Lancet. 2014;384:766-781). In that study, the proportion of adults with a BMI of 25 kg/m² or greater relentlessly increased over time in both developed and developing countries.

"In fact, no country has experienced a decrease in obesity rates over essentially the past 40 years, which is a pretty sobering statistic," Kaplan observed.

"We may disagree over what the primary cause of obesity is, but the final pathway, by its nature, has to be pathophysiological, not merely voluntary control of energy balance," he said.

Why this shift in thinking is so pivotal comes down to understanding what drives people to overeat and gain weight, Kaplan continued.

Physicians who treat obesity naturally take a history to identify triggers for eating, exercise patterns, stress levels, sleep patterns and related circadian rhythm imbalances, and any drugs that can promote obesity.

Overeating does not cause obesity, obesity causes overeating.

"We take that history in detail and then we say to the patient, 'eat less and exercise more'," Kaplan quipped. But this statement reveals little understanding of the biologic basis of obesity or its heterogeneity.

The body defends a fat mass just like it defends a mass of red blood cells, he explained.

"If you try to perturb your red blood cells by donating blood, your body will bring it back to where it was before you gave blood," he pointed out. Similarly, if a patient undergoes liposuction to remove fat, the fat will grow back to where it was before removal, and it will grow back "lumpier and bumpier" than before.

"If there is a pathophysiology that maintains extra body fat beyond what is normal or healthy, then that pathophysiology will drive us to overeat in the case of obesity," Kaplan said.

"Overeating does not cause obesity, obesity causes overeating. Analogously, undereating does not cure or solve the problem of obesity, effective treatment of obesity causes undereating," he stressed.

This brings physicians to an important question: What works in obesity management and what, predictably, does not.

What Might Work in Weight Loss

If obesity is a pathophysiologic state, then the treatments used to modify this state need to be physiologic in nature to drive down the elevated fat-mass set point that propels people to overeat, Kaplan explained.

The obesity treatment arsenal includes a healthy diet, exercise, stress reduction, improved sleep health and the re-establishment of normal circadian rhythms, antiobesity medications (such as metformin and liraglutide) that promote weight loss, and bariatric surgery.

Interventions that don't usually work, at least over the long term, include calorie restriction on a diet chemically unchanged from what patients were eating before (what Kaplan jokingly referred to as the half-Twinkie diet); malabsorptive drugs like orlistat (Xenical, Roche), the only antiobesity drug currently approved by the US Food and Drug Administration specifically for the treatment of pediatric obesity; and devices like the intragastric balloon that restrict food intake or cause malabsorption.

More exercise, if patients are already exercising regularly, is unlikely to promote significant long-term weight loss, Kaplan added.

Each antiobesity intervention "works well in only a small subgroup of patients. There is an enormous variability in response to these interventions," he cautioned.

This suggests that there are multiple subtypes of obesity, which, if defined better, could be used to predict how well a patient might respond to a particular intervention. But accurate predictive models have not yet been developed.

In the meantime, Kaplan and his team are exploring the potential of a genetic risk score to help determine the likelihood of an individual's response to a particular therapy.

"The power of genetics to help guide treatment of obesity is largely untapped," Kaplan said. "But as we learn more about the heterogeneity of obesity, I anticipate that we will be able to provide more individualized and effective treatments, which ultimately will lead to more effective obesity-prevention strategies."

Individualized Treatment

The concept of obesity as a physiologically driven chronic illness that requires treatment with physiologic-based interventions makes sense, said Amy Fleischman, MD, director of the Optimal Weight for Life Program at Boston's Children's Hospital. And she agrees with Kaplan that treatment must be individualized to maximize the chance of success.

"We have a variety of offerings in our clinical program," Fleischman told Medscape Medical News. "We offer individual visits, group visits, exercise programming, and nutritional groups because we believe that different things work for different children and families."

"We also focus on treating the whole family," she added.

Another key element for success is to identify small steps that patients and their families feel are doable, rather than imposing larger goals that they might not be able to sustain.

"In growing kids, the goal is sometimes not weight loss at all," she explained. "Even in our tertiary care center, where we see extreme obesity, we initially focus on slowing the acceleration of weight gain."

The first goal in a growing child is stabilization of the BMI percentile. When kids are still getting taller, their BMI will improve over time with a slowing in the acceleration of weight gain," Fleischman added.

Kaplan serves as a scientific consultant to AMAG, Gelesis, GI Dynamics, Johnson & Johnson, Novartis, Novo Nordisk, Rhythm, Sanofi, and Zafgen. Fleischman has disclosed no relevant financial relationships.

Pediatric Academic Societies (PAS) 2018 Meeting. Presented May 5, 2018.

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