Looking at before-and-after photos of British pooch Oscar, you'd be forgiven for thinking they were two different dogs.
The contrast rivals even the most unrealistic of weight loss adverts.
But make no mistake, the photos aren't just of the same dog, but a prize-winning one at that.
As recently as April, the 10-year-old spaniel weighed a whopping 22kg and was breathless just standing still.
But six months later Oscar was crowned Pet Fit Club Champion, having shed a whopping 40 percent of his bodyweight.
Oscar's owners are overjoyed he's gotten his energy back.
"[He's] very much got his mischievous puppy traits back," Karen Allen says.
Hydrotherapy - water-based exercise - was key to going from fat to fit, along with a very strict diet.
"Dad used to do Sunday roasts, and [Oscar] would have his own Sunday roast," Ms Allen says.
But what might seem like a treat can be trouble, according to vets.
"Even in cats, a tin of tuna is equivalent to 35 chicken nuggets. So what you think is healthy, and a bit of a treat, and is okay, is actually a huge amount of excess calories for that small animal."
Now Oscar's lost the pounds he seems to know what's good for him, and has gone cold turkey on the hot dinners.