Some are calling liraglutide, a new drug approved for weight loss a "gamechanger" in the fight against obesity, but a new study finds the drug also carries significant side effects.

Liraglutide, marketed under the name Saxenda, is an injectable diabetes drug that was approved in Canada for the treatment of obesity in February, 2015. At the time, the drug's manufacturer, Novo Nordisk, was told to conduct further safety testing.

This resulting study found that the medication helped obese people lose close to 20 pounds in just over a year.

But several side effects  among the 3,700 participants were also noted, including nausea, diarrhea, constipation, and vomiting. Other more rare side effects include pancreas inflammation, gallbladder disease, lowered kidney function, and sudden drops in blood sugar.

Liraglutide is a new kind of weight loss drug and is called a glucagonlike peptide-1 receptor (GLP-1) agonist. It works by slowing down the stomach, keeping it full longer so appetite is reduced.

In this latest study, funded by Novo Nordisk, those taking the drug lost an average of eight kilograms or 18.5 lbs, over 56 weeks. Those taking a placebo only lost 3 kg, or 6 lbs. CTV health and medical expert Dr. Marla Shapiro says that is considered a "quite significant" weight loss.

"Two-thirds of the individuals met the target of losing at least five per cent of their body weight," she told CTV's Canada AM Thursday.

"And we use that as a marker because if you can lose five per cent of your body weight – regardless of where you start – we begin to see significant changes" in overall health, she said.

That includes improvements in blood pressure, waist circumference and the delayed onset of Type 2 diabetes.

But Shapiro noted the study also found that patients' weight returned when they stopped taking the drug.

"(They) began to see regain again, on average about 2.5 to 3 kilograms. So it may be, in fact, that this becomes a lifelong medication," she said.

Still, Shapiro notes liraglutide has performed much better than other weight loss medications currently on the market.

"It's encouraging that there's something new on the market, whereas up until now, there really hasn't been anything that we've been able to sustain or that hasn't been pulled off the market."

The study was double-blind, meaning neither the patients nor doctors knew who was taking the real drug or the placebo. All study subjects were also given lifestyle training to improve their eating habits.

The full results appear in this week's New England Journal of Medicine.