Obesity and diabetes researchers Zubin Panthaky and Katherine Morrison share information about how weight-loss drugs work and what we still have to learn. (Adobe Stock Image)
Diet and exercise have long been relied upon to tackle obesity, a chronic disease that affects 30 per cent of Canadians, but researchers say the arrival of a weight-loss-focused drug could be a big catalyst for people who need extra help getting healthier.
Weight loss drugs are nothing new in Canada. The first drug approved for use was Xenical in 1999. Now, more than two decades later, not a day goes by without hearing about a drug like the diabetes treatment Ozempic, which saw a surge in popularity in 2023 after it was shown that its active ingredient, semaglutide, could aid in weight loss.
Semaglutide is also the main ingredient in Wegovy, a weight-loss drug that entered the Canadian market in May 2024.
We spoke to Zubin Pantaky and Catherine Morrison, obesity and diabetes researchers at McMaster University, about weight loss drugs, how they work, and how they can be used in adults and children.
What is semaglutide and how does it work?
Semaglutide is a glucagon-like peptide-1 (GLP-1) receptor agonist, which means it acts like a hormone called GLP-1, which is produced naturally in the human body after eating.
This hormone tells your brain when you’re full, and it also slows down how quickly food leaves your stomach, so you feel fuller for longer.
“So we tend to feel fuller for longer during or after a meal, and as a result, we may not get the signals that trigger us to eat more,” said Panthaky, an associate professor of medicine and member of the Center for Metabolism, Obesity and Diabetes Research (MODR).
The drug is currently recommended for use in adult patients with at least one associated condition – hypertension, type 2 diabetes, dyslipidemia, or obstructive sleep apnea – who have a body mass index (BMI) of 27. It can also be prescribed for children aged 12 years and older.
Panthaky said taking the drug can cause several side effects, including nausea, vomiting, constipation and diarrhea.
Some people see loss of appetite as a side effect because they dislike the fact that they no longer enjoy eating, he says, “which is why some people stop taking the medication because it’s too effective.”
How does this medication relate to weight loss through diet and exercise?
There’s a misconception that losing weight is easy – just eat less and exercise, but Morrison says brain biochemistry plays a bigger role in weight loss than most people realise.
“This is not a cognitive issue; it’s about sending signals to the brain that you’re hungry,” said Morrison, a professor of pediatrics and co-director of the MODR.
“We think that biologically there are clearly differences between people, and that some people have much stronger appetite urges than others.”
Obesity is a chronic health condition, just like diabetes or hypertension, and while drug interventions are always preferred for treating obesity, they aren’t always effective, Pantake said.
This is where drugs like Wegovy come in handy, as it affects the signals sent to the brain and can disrupt the brain’s signals that tell the body that it’s still hungry.
Can these drugs be used to help obese children?
Semaglutide is approved for use in children aged 12 and over, but there is limited research evaluating its long-term effects, Morrison said.
More research is needed, but if the drug is administered, it would be best used with adolescents who have health problems, she said.
“My view is that if we were to use this, we would focus on health aspects, not size,” Morrison says. “Families would agree that this might improve their child’s health, and then they would consider implementing it.”
Morrison is part of a group working to develop new clinical practice guidelines to help clinicians and families decide the best approach, expected to be published in late 2024.
“Our fundamental approach is to encourage families and children to focus on healthy nutrition, regular exercise, reduced screen time, good quality sleep and good mental health.”
What about the long-term sustainability of these drugs?
Morrison and Pantaky say more research is needed to understand what happens when the drugs are stopped or if they are used long-term.
“There’s a lot to learn. We only have a year’s worth of data on children. We don’t know the long-term impacts, but I think it’s important that families understand that before they make this decision,” Morrison said.
And most of the studies in adults have looked at semaglutide’s use to treat diabetes, not for weight loss, Panthaky noted, but based on the evidence so far, there are no known harms, he said.
“In fact, studies have shown that this drug can not only reduce heart attacks and strokes, but also kidney complications from diabetes,” Panthaky says.
When patients stop using these weight loss drugs, their appetite may return and they may feel less full.
