"Skinny Vinnie," formerly known as "Fat Vincent," is living his best life

No one really knows how the 9-year-old dachshund, Vincent, became double the healthy weight for his breed, except for one thing: he loves fast-food.

“Vinnie was turned into the shelter as ‘Fat Vincent,’” says Melissa Anderson, the dachshund rescuer who adopted him. “He literally could not walk. We don’t really know how Vincent became obese. I do know that when I go through a drive-thru, he goes crazy.”

The pup, who was found at K-9 Angels Rescue of Houston, began his weight loss journey at 38 pounds last August, making him morbidly obese for a dog of his size.

His transformation began in the swimming pool. In an effort to get him active, Anderson would put him in the pool for swims.

“Slowly but surely, he started to move,” she says.

After nearly a year of dieting, exercising, and love from his newly adopted family, “Fat Vincent” has a new name … “Skinny Vinnie.” The pup now weighs in at a healthy 15 pounds.

For more on Skinny Vinnie’s transformation, tune in to PEOPLE’s List, Saturday July 2, 8/7c on ABC.

“He’s a very good example of strength and endurance,” Anderson, 54, says. “We all marvel at his accomplishments because we’ve been here with [him] the whole time and not for one day has he been reluctant or expressed any kind animosity about all of the things he’s had to do like limit his food and follow the rules of this house.”

The most exciting change in Vinnie is his new energy level, though he still has many of the insecurities that are common to rescue dogs.

“He’s always looking to see where I am and when I leave and come home, he’s the happiest dog in the house that I’m home,” she says. “It’s just that feeling I have that he’s worried [about] when am I going to leave and never come back again.”

While she initially planned on fostering Vincent until she could find him a new home, she now “can’t imagine letting him go.”

“We just want him to know what a forever home is,” she says. “I thought I could find him the best home ever with all the publicity he’s gotten — he’d probably be flying on private jets, you know. But, I just feel like I don’t want him to go through it again. I just really feel like he needs to stay right where he is.”