Rosie explained that she had no plans to gain further weight.
"I don’t want to become 600 pounds and bedridden, my goal is to be plus size and be happy and healthy," the mother-of-one said.
"I am not gaining weight constantly I am comfortable at the weight I am, I have stabilised it."
She added: "Some people may say it isn't responsible but we’re definitely happy and content in our lives and not doing anything to harm anyone else."
Asked by presenter Philip Schofield what he found attractive about Rosie, Jeff, who goes to the gym four to six times a week, said: "As you can see she is quite a large lady, it is hard to put a finger on it, she just floats my boat is that how you say it…?"
Rosie reiterated that she would "be the same weight with or without Jeff", adding she felt "confident and sexy" with her body.
"I feel confident and beautiful and sexy as a woman. I would still continue to be this person even before I met him. Just because I have had this gain of weight.
"I feel more confident and sexy the more I weigh. I go out in a bikini to the beach like everyone else, I wear tight clothes like everyone else. I just feel comfortable in my own skin. If I was smaller I wouldn’t feel confident."
Jeff added, "In today's society a lot of things are about objectification our relationship definitely isn’t that we got to know each other on a deep emotional level before physical attraction."