Key points from article :
Lorcaserin did not increase risk of heart attack or stroke.
Drug can be prescribed in US but is not approved in Europe.
Average weight loss was 4.2kg compared to 1.4kg for placebo.
Combined treatment plan also included dietary changes and exercise.
Randomised controlled trial of 12,000 overweight & obese people.
The study was published in the New England Journal of Medicine.