Her claim to fame was being Britain’s fattest orang-utan, but now Oshine is a shadow of her former self.

Monkey World ape rescue centre near Wool imposed a strict diet on the podgy primate, who weighed in at more than double the natural weight of a female orang-utan.

Rescued from South Africa in August last year, where she had been kept as a pet for 12 years, Oshine the Bornean orang-utan tipped the scales at 100kg.

But following a health and fitness programme, which included cutting out sweets and processed food and living with five others of her species, she has lost a quarter of her original body weight.

Oshine now weighs 75kg and exercising with her new family, is scaling a 20m climbing frame with ease, and has even adopted an orphaned baby orang-utan called Silvestre.

“The O-diet has worked amazingly well for Oshine,” said Dr Alison Cronin, director of Monkey World.

“She has steadily lost a quarter of her body weight, amounting to 25kg over the year, and without it being too hard on her.

“Oshine has been eating a healthy diet of fruit, vegetables and lean protein the same as the rest of our orang-utans.

“Combined with the exercise of climbing and playing with the youngsters in our orang-utan crèche, she is much healthier and a lot more active.”

She added: “Oshine still has more than 20 kilos to lose but we are so happy for her and pleased that her health has improved.”

As with humans, her obesity left her at risk of suffering from high blood pressure and type two diabetes.

The 'O-diet'

Daily

One apple or pear

One banana

Two carrots or parsnip

Small handful of fine beans

Two portions of soft fruit – plum, kiwi, melon, grapes, oranges, or tomato

One portion root veg – turnip, celeriac, or swede

Two cereal biscuits – such as Weetabix

Broccoli

Cabbage or greens

Celery

Cucumber

Leek

Mooli or radish

Lettuce

Treats – a few grapes every day

Weekly

Two eggs per week

One chicken breast per week

One cup of rice or cous cous per week