To cure obesity, we need therapies that address overeating’s link to depression, mood disorders
Kirsty Wigglesworth/AP filesObesity is a persistent problem that kills many people every year and which we don't entirely understand, Dr. David Macklin, an expert on the disease, writes.
As a family physician whose practice deals exclusively in the treatment of obesity, it strikes me as remarkable how little we understand the disease, which is Canada’s second-leading cause of preventable death.
Recently, though, the fight against obesity is showing signs of joining the 21st century. For example, this autumn many in the medical profession expect the Food and Drug Administration in the United States to approve what I believe will be a really promising pharmaceutical therapy for obesity.In every region of the developed world, rates of obesity doubled in the 20 years between 1988 and 2008, according to World Health Organization, which now counts more than a half-billion of Earth’s population as obese. The Public Health Agency of Canada says obesity costs our country somewhere between $4.6-billion to $7.1-billion every year. Even with these stark facts, the most effective long-term therapy we’ve come up with to treat the disease is bariatric surgery — a comparatively radical procedure that sees a surgeon restrict the size of the stomach, or cut off a piece of it.
The drug’s development stems from an evolving understanding of a certain type of overeating that arises from stress-triggered depression. The path to obesity may begin for some people with a stressful event that the person perceives as threatening — ranging from early life abuse to the loss of a job or a loved one. The resulting release of stress hormones interferes with the brain’s stimulus-reward circuitry. Essentially, the stress takes away one’s ability to feel pleasure. The resulting condition is referred to as “anhedonia,” and it’s one of the two primary symptoms of depression.
The next step sees some anhedonia sufferers go off in search of other ways to activate their reward circuitry and feel pleasure. Most of the options remaining to them are unhealthy. Drugs and alcohol will get the job done, as can three substances that are far less regulated than intoxicants — sugar, salt and fat.
With few other options available to feel pleasure, the anhedonic person turns to the consumption of calorie-dense foods to fire their pleasure receptors. And over time, conditioning leads to a powerful drive to overeat — with stress and common settings such as a couch and a TV triggering an overwhelming impulse to consume.
We live in a stressful world where we have virtually unlimited access to sugar, fat and salt — foods laden with them are available at any time of day, nearly anywhere, and are often super-sized and inexpensive. Throw stress at us and studies show that while 30% of us will lose weight, the remaining 70% of us will eat more and gain weight. And interestingly, 70% of Canadians are obese or overweight.
I have spent more than 12,000 hours treating obesity in the last 10 years and it is becoming increasingly apparent to me that this stress-anhedonia-overeating pathology may be contributing to the struggles of a majority of my patients.
Understanding that a link exists between stress, depression and obesity is allowing the pharmaceutical industry to tailor treatments to address the connections and the pathway that makes them possible. For example, a California-based company called Orexigen Therapeutics is in the final stages of seeking FDA approval for a drug it’s marketing under the name of Contrave. The pharmaceutical therapy actually is a combination of two drugs — an anti-depressant, buproprion, and naltrexone, an anti-addiction drug currently used to treat people for alcohol dependence. The buproprion alleviates the anhedonia that triggers the overeating, and in clinical trials, Contrave, combined with behavioural modification treatment, helped subjects lose an average of 10% of their body weight. And 10% weight loss is sufficient to treat early-stage diabetes. It’s expected to be approved by the FDA this fall, suggesting the possibility of a similar decision down the road by Health Canada. And other pharmaceutical therapies that combine anti-depressants with other drugs also are in the pipeline.
More exciting than any single drug, though, is the fact that the medical profession is developing new and more sophisticated ways to manage overeating itself. Will the new understanding stem the rise of obesity-related deaths? Could treatments based on our new understandings of why many overeat help you, or someone you know, address a developing weight problem? The only certainty is that the medical profession needs more tools, in addition to surgery, to address the growing obesity epidemic — and with new behavioural and pharmaceutical treatments we are getting them.
—Dr. David Macklin directs the weight management program at the Medcan Clinic, a leading preventive health clinic in Toronto. Dr. James Aw is on sabbatical. For more information, visit medcan.com.
