Subjects were randomly assigned to receive an injection of either exenatide, 10 micrograms twice a day (73 subjects), or placebo (79 subjects), along with a structured lifestyle modification program involving diet and exercise, for 24 weeks. Neither the subjects nor the staff giving the treatments knew which individuals received the study medication. There was no statistically significant difference in beginning weight between the exenatide-treated subjects and the control subjects, who got the placebo injection.

Individuals who received exenatide lost more weight in 24 weeks than controls did, the authors reported. Those who received the medication lost an average of more than 11 pounds (5.06 kg), whereas the controls lost just 3.5 pounds (1.61 kg). This difference was statistically significant and noted as early as week 8. Only exenatide-treated subjects lost more than 10 percent of their body weight (seven of 73 subjects, or 9.6%).

The most common side effects of exenatide were mild or moderate nausea and diarrhea, but weight loss was independent of nausea, the authors reported. Although exenatide lowers blood glucose, or sugar, levels in people with diabetes, it is known to only act in the presence of high blood glucose so that no subjects reported low blood sugar.

Possible reasons why exenatide may cause weight loss include decreased food intake and increased feelings of fullness, he explained.

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