Oscar the dog used to love tucking into his fave food of sausages, roast chicken and creamy pasta.
But the 10-year-old Labrador's weight ballooned to 48kg and he collapsed under the weight.
On a new strict diet and exercise programme he's lost about 10kg - and has been named pet slimmer of the year!
Owner Louise Critcher said losing weight had changed his life. "He's full of life, has tonnes of energy, his coat is glowing and his eyes are sparkling."
He came first in a 100-day diet competition, organised by the vet charity the People's Dispensary for Sick Animals (PDSA).
Mrs Critcher, from Hamilton in South Lanarkshire, Scotland, said: "At the beginning Oscar didn't take to the diet and used to look at us, as if to say 'Is that it?'
"But he soon got used to it."
George the cat
In joint second place were 10-year-old cocker spaniel Poppy from Nottingham, who lost 5.5kg, and 13-year-old mongrel Scooby from Gillingham, Kent, who shed just over 2kg.
Overweight cat George, from Everton in Liverpool, took third place after losing more than a kg.