Clinical psychologist Professor Tanya Byron believes that the only way to beat it is to separate the couples and give them therapy that can address their individual issues and make the change for good.
Becky and her partner Phil over-eat, they knock back three litres of fizzy drinks every day and Phil's weight has been as much as 30 stone. Meanwhile, Becky always caves in to takeaway temptation.
Tanya and her team separate them for 10 weeks in a bid to overhaul their habits. Can they manage to help these two be happier and healthier?
Weight For Love, BBC1, 8pm
Follow us on Twitter @RevealMag for all your celeb, fashion and beauty news!