Fat Boy is now on a diet. (Moose Jaw Humane Society)

An effort by the Moose Jaw Humane Society to have an obese cat shed a few pounds is attracting attention on Facebook.

The saga of Fat Boy, who recently went on a strict diet, is being chronicled on the social networking site.

The cat, which is around eight years old, had grown to an alarming 10.4 kilograms (23 pounds) before the shelter was advised to take action about his weight.

'People will come to the shelter just to see him' —Karla Pratt, Moose Jaw Humane Society

He was given to the agency in 2006, when he was known as Boots, and eventually joined three other cats as the shelter's resident felines.

The animals shared a feeding station but Boots was quick to the bowl and before long he had grown to Fat Boy proportions.

Now, all four cats that live together are on reduced rations.

"They're not all very happy about this," Karla Pratt, the promotions coordinator for the society, told CBC News Tuesday.

Sneaking snacks

Staff have also rigged up a box system, so the smaller cats can get to their food but Fat Boy can not get through the opening to steal from them.

Every Friday is a weigh-in day and Fat Boy's progress is noted on the shelter's Facebook page.

After four weeks of the trimming regime, he is down to 10 kilograms (22 pounds).

It was tough making progress as, initially, he lost a few grams and quickly gained them back.

Staff discovered Fat Boy was reaching into other cat pens and tipping bowls to scarf down the scattered contents.

"People will come to the shelter just to see him," Pratt said of the cat's popularity in the city.

Facebook page encourages others

"We've had lots of positive feedback," she said, in reference to the diet plan, noting it raises awareness of the importance of keeping pets on a healthy diet and maintaining a good weight.

Pratt said they are aiming to Fat Boy to be around 6 to 7 kilograms (14-15 pounds).

He is not, yet, on an exercise routine.

"He's a bit of a couch potato," Pratt said.