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Liraglutide was developed from a chemical in the saliva of the Gila monster, a venomous lizard native to the deserts of the Southwestern United States.Getty Images/iStockphoto

THINjection. That's what I call Saxenda, a new injectable medication for obesity that has been submitted to Health Canada for approval and won approval in the United States from the Food and Drug Administration on Dec. 23.

When I tell patients about it, they can't wait. "Give it to me now," says Satish, a 35-year-old man who has been struggling with his weight for years. He doesn't care about possible side effects; he just wants the drug, pronto.

Other patients are similarly excited. "When I try to lose weight, I'll lose five pounds – but I need to lose 50," says Jake, a teenager who says he was "just born fat."

One patient is upset because he listened to me, quit smoking and promptly gained 40 pounds. He hopes the injection will be "the easy way" to weight loss and not require "any self-control."

Many factors conspire to promote obesity and being overweight, conditions which now affect 40 per cent of Canadians. More people spend too much time gaming and socializing on computers. Supersized drinks, burgers and candies are available everywhere. Food also has emotional value (one patient of mine uses "food as a crutch" when he feels stressed) and in many cultures, food is love – so overfeeding friends and family at gatherings is seen as caring and hospitable.

Given this epidemic, the American Medical Association officially declared obesity a disease in 2013. Today's medical students are trained to think of obesity as the new universal evil, because it promotes heart attack, stroke, diabetes, kidney failure and even arthritis (joints are crushed).

Additional approaches to weight loss are desperately needed, as nothing works for too long. Will this new injectable be the answer?

Given the checkered history of weight-loss medications, doctors and patients are skeptical about another "cure." Previous obesity drugs basically revved up your metabolic rate leading to weight loss, but with toxic side effects, including high blood pressure, palpitations and even death. The most notorious of these was fen-phen, a combination of fenfluramine and phentermine. Once this gained widespread use, many people had fatal reactions, including heart and lung failure. Eventually, this led to the withdrawal of this combo, billion-dollar legal settlements – and a robust black market.

This new injectable medication looks promising. The drug is manufactured by Novo Nordisk, the pharmaceutical giant based in Denmark. The chemistry of the new drug, called liraglutide, also known as a GLP-1 agonist, may be a game-changer. Since there are receptors for GLP-1 everywhere, the drug works throughout the body. (Doctors already know Victoza, a low-dose form of this drug for diabetes.)

Speaking at a recent conference in Barcelona, Dr. Chris Sorli, a diabetes specialist at Rocky Mountain College in Montana, noted the package deal of benefits. "It enhances beta-cell function, increases insulin and energy storage, acts centrally on the brain and slows down stomach motility."

This widespread combination of effects is powerful. The medication wakes up and protects the insulin-producing cells in the pancreas, which reduce blood sugar. It speaks to the brain directly, speeding up food satisfaction. And it lets food linger in the gut, as if it's forcing you to eat slowly. (This slower transit through the gut also leads to the most common side effects, nausea and constipation.)

Yet the company didn't originally synthesize the drug in a lab. Believe it or not, the original chemical comes from the saliva of the Gila monster, a venomous lizard native to the deserts of the Southwestern United States. Because of the harsh environment, the critter only eats every three months. While doctors can't recommend dieting like that to patients, we can exploit the chemistry.

What's also smart is that the company is not just targeting diabetic patients, but also obese patients without diabetes, and – most amazingly – pre-diabetic patients. That's revolutionary: In Canada there are about three million people with diabetes, but almost six million with pre-diabetes (people with higher-than-normal levels of blood sugar).

This means that we don't have to wait until you get diabetes to prescribe this drug. We can offer this medication at earlier stages; for example, when you're obese but not diabetic, or when your sugar just starts to drift upward. That's a much-needed revolution in health care and may usher in the era of preventing diabetes in the first place.

Novo Nordisk is still seeking permission to release Saxenda in Canada, Brazil and the European Union. "We are confident in the benefit-risk profile," says Dr. Morten Donsmark, a scientist at Novo Nordisk.

So how much weight do you lose on the new medication?

Of course, the answer varies from patient to patient, but on average it's about six to 11 per cent of your body weight, according to a study published in The International Journal of Obesity, which involved 3,500 patients globally.

As good as the medication may be, however, a single drug won't be the answer.

"I don't think we'll ever have an obesity drug that works for everybody," says Dr. Arya Sharma, professor and chair of obesity research at the University of Alberta. "But I do think additional therapies in the mix will help."

Dr. Judy Shiau, a professor at the Weight Management Clinic at the University of Ottawa, agrees. "I'm encouraged by the potential of the new agent, because obesity is a chronic disease."

So we doctors will have to use multiple strategies, including calorie-counting, counselling, exercise, medications and even surgery, when obesity is severe.

Health Advisor contributors share their knowledge in fields ranging from fitness to psychology, pediatrics to aging. Dr. Shafiq Qaadri, MPP, is a Toronto family physician.

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