Weight loss is difficult. But a new study published in the New England Journal of Medicine provides hope for the obese.

An international trial found that some people lost up to one-fifth of their body weight when injected once a week with the drug semaglutide. Overall, the nearly 2,000 participants in the 15-month trial lost an average of 33 pounds.

Scientists hope the results are the dawn of a "new era" in obesity treatment, according to BBC News, and there are more potential drugs on the way.

A woman identified only as Jan lost more than 20% of her body weight, more than 60 pounds, during the trial.

"The drug changed my life and completely altered my approach to food," she said.

However, Jan said she has gained weight since the trial ended. 

Semaglutide is used as a treatment for type 2 diabetes. The trial dispensed the drug in higher doses. It acts the same as a hormone the body releases after eating a meal, curbing the user's hunger.

In the trial, some received the drug and others got a placebo. Both groups were given identical tips on diet and fitness. Those on the drug lost an average of 33 pounds, those without it lost an average of less than six.

Losing one-fifth of body weight wasn't an isolated occurrence in the trial -- 32% of participants on the drug lost at least that much. Less than 2% matched those results with diet and exercise alone.

There were side effects, which included nausea, diarrhea, vomiting and constipation. Researchers are conducting five-year studies to learn if the weight loss is sustainable.

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