By Julie Mazziotta
Updated October 06, 2016 03:50 PM

Ali Vincent wants to make one thing clear: She never experienced pressure to use drugs or forego water while she was on the Biggest Loser, contrary to recent allegations.

The winner of season five is speaking out against claims made by other former contestants on Saturday’s episode of Oprah: Where Are They Now?.

“There’s a lot of allegations out there now with the Biggest Loser,” Vincent says in an exclusive clip from the episode. “There’s allegations that there’s drugs, and ‘Oh, they’re not letting you drink water!’ It didn’t happen on my season.”

“I find it highly unlikely that it was allowed, and it was recommended, or that it was forced. Because no one can force anybody to do anything on the Biggest Loser. Period. End of story.”

Joelle Gwynn, who competed on season seven of the show, alleged in May that trainer-turned-host Bob Harper gave her drugs.

Bob Harper was my trainer… He goes away and his assistant comes in. He’s got this brown paper bag that’s bundled up. He says, ‘Take this drug, it’ll really help you.’ It was yellow and black. I was like, ‘What the f— is this?’ ” Gwynn told the New York Post. “I felt jittery and hyper. The next day, [the show’s resident doctor, Robert Huizenga] gave us some lame explanation of why they got added to our regimen and that it was up to us to take them… People chastise Bill Cosby for allegedly offering meds to women, but it’s acceptable to do to fat people to make them lose weight. I feel like we got raped, too.”

Harper has adamantly denied all allegations, and producers on the show said that they do not tolerate drug use of any kind.

Vincent says that the contestants have control over what they do or don’t do on the show.

“Yes, you’re in this sequestered situation, but you are making your own choices to do that. You know, it’s like, take responsibility,” she says. “So the allegations are hard for me.”

Vincent, who took home the top prize back in 2008, doesn’t understand why contestants from earlier seasons are only now coming forward with these allegations.

“Two of [the contestants] were two seasons before me. Okay, then why didn’t you say something then?” she asks. “I’m sorry that they had bad experiences but I know that they do not speak for the majority of us. In the most part, everybody finds it a positive experience in their life.”

The Biggest Loser also came under fire earlier in May after a study involving former contestants found that they are unable to keep the weight they lose on the show off because their metabolism never recovers.

Vincent, who announced in April that she had regrettably regained almost all of the 112 lbs. she lost on the show, told PEOPLE that the study might explain why she was unable to keep the weight off.

“After reading the New York Times article, I wonder if it was possibly because of lack of Leptin? I guess I’ll never really know,” she said.

Oprah: Where Are They Now? airs Saturdays at 10 p.m. ET on OWN.