Jennifer Hudson isn't the only one shedding pounds through Weight Watchers. A scientific study finds that Weight Watchers is a more effective way to lose weight rather than visiting the doctor for a standard weight-loss plan.

A new research shows that overweight patients who were told by their doctors to go to Weight Watchers lost around twice as much weight as people getting standard weight loss care over 12 months.

The study published in Lancet medical journal assessed 700 overweight adults in Australia, Germany, and the UK.

Patients were randomly assigned to get either 12 months of standard care usually offered by a primary care physician, or referred to and given a 12-month-long free membership for a Weight Watchers group in their neighborhood.

In addition to losing twice as much weight as their counterpart in the standard care group, the Weight Watchers group were also more than three times as likely to lose 10 percent or more of their initial body weight.

About 61 percent of the patients in the Weight Watchers group lost at least 5 percent of their body weight, compared to the 32 percent in the standard care group. The average weight loss at 12 months was about 5.1 kg for those using Weight Watchers. People in the standard care group lost 2.2 kg.

Those who endured the full 12 months had an average weight loss of 6.7 kg on Weight Watchers versus 3.3 kg on standard care.

Susan Jebb from Britain's Medical Research Council Human Nutrition Research Unit led the study.

This kind of research is important so that we can identify clinically effective interventions to treat obesity, Jebb told Reuters. She also said the results showed that Weight Watchers is a robust intervention that is generalizable to other economically developed countries.

David Kirchhoff, the chief executive officer of Weight Watchers International, said the Lancet study proves that Weight Watchers is part of the solution to help transform the health of nations.

There is a clear need for practical treatment solutions that are proven effective, affordable and scalable to have a population-wide impact, Kirchhoff said in a statement.

Click on the slideshow to see Jennifer Hudson's transformation using Weight Watchers.