The drug, called retatrutide, is being developed by pharmaceutical company Eli Lilly.
The findings were presented at the American Diabetes Association conference in New Orleans.
One of the trials included 2,339 people with obesity. Participants received different doses of the medication over an 80-week period.
Those receiving the highest doses experienced the greatest weight loss.
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According to Eli Lilly, some participants lost more than a quarter of their body weight.
Around one in three participants on the highest dose reduced their BMI to below 25.
Known side effects
Researchers also recorded side effects. The most common were nausea, diarrhea, and vomiting.
Some participants also experienced changes in sensation or developed urinary tract infections.
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The drug has not yet been approved and is still being tested in clinical trials.
At the same time, authorities are warning against illegal copies of the medication, which, according to The Sun, are being sold through social media.
More than weight loss
Researchers also examined other health effects.
Another study involving 537 people with type 2 diabetes showed, among other findings, improvements in blood pressure.
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However, the most striking part of the results came from analyses of obesity-related conditions.
According to Eli Lilly, the severity of sleep apnea was reduced by 60 percent among participants with obesity.
At the same time, pain caused by knee osteoarthritis decreased by up to 73 percent.
The findings therefore suggest that retatrutide may affect several of the diseases that often accompany obesity.
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Sources: The Sun and American Diabetes Association.
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