A documentary featuring the post-mortem examination of a 17-stone (108kg) woman has revealed the devastating impact obesity has on the human body.

Obesity: The Post Mortem examines what happens inside the human body when a person is overweight — the first time in the UK a post-mortem has been carried out for this purpose.

The gruesome discoveries include a “paper”-thin heart and an abdomen full of “yellow greasy fat”.

Pathologist Dr Mike Osborn, a consultant at the Royal College of Pathologists, and assistant pathology technician Carla Valentine carried out the procedure on a female donor to show what excess fat does to vital organs.

The hour-long BBC Three documentary, which is available online, features a woman in her early sixties whose body was transported 5,000 miles from Long Beach California to the pathologists’ table in London.

The woman was classed as clinically obese before she died of heart failure. Osborn said obesity “led to changes in the heart which meant the heart failed, it couldn’t work properly, and that’s what this lady died from”.

The woman’s heart was described as like a “paper bag” (BBC/iPlayer)

Osborn described her liver as soft as “pate” because of the impact of obesity. It also led to her heart becoming as thin as a “paper bag” because it pumped harder and harder, he suggested.

Osborn said: “[Her] left ventricle is very, very thin. That’s because she developed high blood pressure. Basically you go from a thick muscular pump to a paper bag that isn’t capable of pumping blood around the body.”

He added: “The findings in the heart were extremely marked and the severity actually surprises me.”

The woman was cut open by Valentine using a large and deep single cut starting at the top of neck which revealed “an awful lot of yellow very sort of greasy fatty tissue”.

She described it as “like butter with a mesh going through it”.

Dr Osborn and Ms Valentine cut open the 17-stone body (BBC/iPlayer)

The film, made by production company 7 Wonder, also features a cast of young people who reveal how biology, psychology and food have contributed to making them fat, and what it means to live with obesity.

Osborn said: “Everybody knows what obesity looks like from the outside but unless you have a job like ours most people don’t see what obesity looks like from the inside.”

:: Obesity: The Post Mortem is available via bbc.co.uk/bbcthree