'1000-Lb. Sisters' Star Tammy Slaton Achieves Goal Weight Ahead of Surgery

Tammy Slaton is celebrating a major milestone in her weight loss journey after entering rehab. The 1000-Lb. Sisters star, 36, learns she has dropped over 180 lbs. to hit her goal weight in order to undergo weight loss surgery in a preview of Tuesday's all-new episode of the TLC show shared by PEOPLE.

Tammy, who had hit her highest weight of 717 lbs. when she first arrived at the weight loss rehab facility in Ohio, is with sisters Amanda and Misty when she learns about the progress she's made. "I need to get to 550 lbs. for me to be approved for surgery," Tammy says in the clip. "Until then, I hate getting on a scale. My worst fear is gaining weight. I don't want to disappoint my family or myself."

Stepping on the scale, Tammy learns she's now weighing in at 534 lbs., which is 16 lbs. under the 550 lbs. marker her bariatric surgeon, Dr. Eric Smith, set before the TLC star would be able to undergo weight loss surgery. "When I got on the scale and I saw the scale was at 534.7, I kinda stopped breathing for a second," Tammy says. "I'm like 14 lbs. under my goal weight. From over 700, that's a huge drop."

"I did that!" she continues excitedly. "I'm feeling thrilled, proud, excited – just all the emotions. I proved everybody wrong. Everybody that doubted me, I finally got mine! My told-you-so moment!" It's good news for not just Tammy, but also Amanda and Misty. "This is what we've been waiting for. This is what we've been working for," Amanda says in a confessional. "Tammy's made the goal weight, it might mean she's finally gonna have surgery. She's finally gonna get this and the future looks good."

"I know there's several other doctors that she has to get approved from but the way I look at it is, before we can ever go see those people she had to reach that weight loss goal that Dr. Smith had given her and Tammy's done that," she continues. "She's gonna do the damn thing." 1000-Lb. Sisters airs Tuesdays at 9 p.m. ET/PT on TLC.