An obese monkey who was sent to "fat camp" two years ago to lose weight now looks fighting fit, posing in a swimming pool with glistening fur.

Named "Godzilla," the monkey had weighed 19kg (41.9 lbs) -- nearly double the standard weight of normal macaques -- before he was rescued from a market in Bangkok, Thailand in March 2021.

Authorities had found him chained up and bloated with well-meaning passers-by killing him with kindness by feeding him high-sugar treats like fruits, nuts, and sweet drinks.

He was sent to a wildlife centre in Chachoengsao province, where he was put on a strict diet of dill, lettuce, crickets, worms, sunflower seeds, and other nutritious food.

Photos taken in February this year, almost two years after he was rescued, show Godzilla looking healthier and happier as he frolicks in a pool at the Crystal Pet Hospital, a veterinary center in Bangkok.

Staff said that Godzilla had dropped from his previous 'dangerously unhealthy' weight of 19kg and now weighs around 15kg.

A spokesman said: "Godzilla has been eating healthily. He hasn't had a single bit of junk food. He is friendlier and happier and can interact with other monkeys without attacking them.

"He loves swimming. That's his favourite thing as he helps him to cool off.'

Godzilla's former owner Manop Emsan and his family are allowed to visit Godzilla and play with him in the pool.

They claimed they took him in originally when his parents were killed by a car when he was a baby and a previous owner had abandoned him.

The family kept the monkey as a pet -- illegal under the country's wildlife laws -- and let him snack all day while he ran his stall selling meatballs.

Bureau of Wildlife Conservation officials said Godzilla would not be allowed to return to the family as keeping him as a pet is illegal and he will not be released into the wild as he will struggle to survive alone.

The monkey will now stay at the wildlife centre indefinitely.

Supasek Sarachitti, the director of Crystal Pet Hospital, had previously diagnosed Godzilla with Cushing Syndrome, which causes weight gain through overproduction of the stress hormone cortisol, as well as diabetes.