“There are some serious ethical, financial and efficacy considerations with such an approach,” said obesity specialist Dolly van Tulleken, a visiting researcher at the epidemiology unit at the University of Cambridge. “Such as looking at people — or measuring people — based on their potential economic value, rather than primarily based on their needs and their health needs,” she told the BBC on Tuesday.

Van Tulleken argued that people who are eligible should be able to receive the treatment, but warned that this must be coupled with measures to ease healthy food choices.

“You can treat people all you want, but if we’re putting them back into the conditions that made them sick in the first place, it’s incredibly important to stop that — and that very much lies with our food environment.”

Another concern is the scale of treatment needed. While the study will enroll 5,000 people with obesity, more than two-thirds of the adult population is overweight or obese.

However, the NHS has forecast that these medicines would have the greatest benefits for up to 300,000 people, James Bethell, a health minister under the former Conservative government, told the BBC Today program.

This article has been updated.