Weight-Loss Secrets From a Formerly Obese Dachshund

Thanks to some dogged determination, Internet celebrity and obese dachshund Dennis is the latest weight-loss success story in the animal kingdom — registering 12 pounds on the scale today, down from 56 pounds in 2013.

Now you’re probably wondering — what juice cleanse did he do? Where does he go to spin class? Which celebrity diet did he follow? The answer is none of the above, just good old-fashioned cardio like chasing squirrels in the backyard and playing fetch. Plus, he now subsists on dry dog food instead of hamburgers and pizza.

“In the beginning, you could tell he was very depressed, that he really didn’t feel good at all. He didn’t have much of a personality,” says owner Brooke Burton, 26, a nursing student, who told the Associated Press that as the six year old lost weight, he would “trip over” the folds of skin, which also got infected and required three surgeries to remedy. But now that he’s slimmer, “this bossy little demanding man popped out.’

Read next: 7 of the Cutest Chubby Pets

Write to Olivia B. Waxman at olivia.waxman@time.com.