Janet, 40, and Laura, 21, shed the least weight in the opening week of the reality show, which meant that they were in the vote-off. Janet managed to shed 10lbs during the week, but daughter Laura only managed to lose 5lbs.
Sisters Ayanda and Zandela were also in the vote-off after they finished last in a marathon bike ride challenge set by trainers Angie Dowds and Richard Callender.
However, in a tearful final vote, three of the remaining couples voted to eliminate Janet & Laura, meaning that host Davina McCall had to send them home.
Speaking to the remaining contestants, police officer Janet told: "I won't give up. I said that if I got eliminated first that I would lose more weight than the Biggest Loser. So you'd better, really, really work hard, because I'm going to be coming in the back door now."
Afterwards, she continued: "The Biggest Loser has been an amazing experience. I've never worked harder in the gym and I'm really pleased with what I've lost."
Laura added: "We've got the tools and the knowledge now. The future is bright; the future is slim."
The Biggest Loser continues next Monday at 9pm on ITV1.