Researchers will also monitor how it effects a patients job prospects.
The announcement of the trial came after Health Secretary Wes Streeting said the drugs could be given to help people get back into work.
But front line charities in Greater Manchester said they receive few cases of people living with obesity struggling to get and hold down a job.
Jennifer-Anne Smith, chief executive officer of Salford charity Loaves and Fishes, said fewer than 500 of their 6,000 users struggled with the condition.
She said the main obstacles for those out of work was a “tick-box” model at the job centre which meant those with specific needs could not get support.
“To be honest it’s not something that presents as a barrier to employment, unlike mental health, digital exclusion, living in poverty or insecure housing”, Mr Green said.
“We support residents with multiple-barriers, when they tell us what’s standing in their way it’s those issues” and not obesity, he said.
