Viewers were made aware of Wolff's proposal plans during the one-hour special's opening as he flaunted the engagement ring prior to being the first former finalist to be weighed in.
"Tonight, right here, I'm going to be proposing to my lovely Amy Hildreth," Wolff, who was already married when he competed on The Biggest Loser's third season and met Hildreth, gushed to new The Biggest Loser host Alison Sweeney when he came out from backstage for the special's first reunion weigh-in.
However Hildreth was unaware of her boyfriend's plot until it was her turn to come out from backstage and weigh-in as the special's ninth and final participant.
"Well Amy, your starting weight was 260 pounds. Your current weight is..." said Sweeney to Hildreth as she stood on the show's giant scale. But instead of the former finalist's current weight appearing on the screen, it flashed the message "Amy I Love You."
"What's going on? What's going on?" Hildreth questioned as she waved her hands and jumped as Wolff rose from his seat near the studio audience and began approaching Hildreth. "Whoa... What are you doing?" she asked.
"Well, I wanted to bring you here in-front of our Biggest Loser family to ask you something," said Wolff before Hildreth cut him off. "Stop!" she said, giving him a gentle swat.
"But first, I do have a letter," continued Wolff. "'Amy, you're the most incredible woman I've ever met. Your drive for life, sense of adventure, compassion, loyalty, bravery, strength -- all these things make me want to be with you every day of my life. I came here to lose weight and I found my soul mate. I want to take care of you forever.' And I wrote that to you and tonight I just wanted to tell you that I want to keep that promise forever and so I want to ask you..."
As Wolff assumed the position on bended knee to pop the question, all Hildreth could muster was, "No... I'm so... This is crazy..."
"Will you marry me baby?" he asked.
"Yes... Yes, I love you," answered Hildreth through tears as the two embraced, kissed and shared whispers of, "I love you."
"Come on, let me put this on you," said Wolff as he slipped the engagement ring on her finger. "I'm like, shaking," said Hildreth. "I'm shaking too, I know..." Wolff replied.
As for The Biggest Loser: Where Are They Now? reunion weigh-ins, Wolff's weight when he began the competition in 2006 was 365 pounds. He currently weighs 240 pounds, a difference of 125. The Biggest Loser 3champEric Chopin also showed he's continued to keep the weight off, tipping the scale at 231 pounds, a difference of 176 pounds from when he originally started the competition at 407 pounds.
In addition, fellow former The Biggest Loser 3 finalists Pam Smith (247 to 187, a difference of 60 pounds); Poppi Kramer (232 to 126, a difference of 106 pounds); and Mark Wylie (307 to 210, a difference of 97 pounds) all demonstrated that they've been able to keep off the weight they began the competition with last fall (Due to Wolff's marriage proposal, Hildreth's progress was not shown).
The Biggest Loser's fourth-season will premiere with a two-hour special on Tuesday, September 11 at 8PM ET/PT and be followed by another two-hour installment on September 18 before airing 90-minute episodes every week beginning Tuesday, September 25 at 8PM ET/PT.