I don't see this as being such a big dillemma. Clearly, she enjoys her current lifestyle, so I would leave her to it. If she doesn't make any effort to lose weight and instead eats in front of the tv, then it's clear that what she really wants for herself the most is to eat and relax. She knows she will gain more weight, and yet she keeps doing it. That shows me that that is what she wants. Just make sure to keep her comfortable and provide food. Women in general say a lot of things they don't mean, so a better way to gauge her meaning is to look at her actions. Here's a handy translation.
WomenSpeak: "I know I should really be losing weight, but... *grabs pizza*"
English: "I love having the freedom of living this way, but I don't want to admit to being a glutton, so I'll call it something else."
Unless she approaches you for a one-on-one discussion about how concerned she is about her health and then lays out a plan for losing weight, I would just ignore her casual weight loss comments and keep pampering her.

Elaine tells Malvineous that it's been fun, but it's getting late and she should get back home. She gives Malvineous a peck on the cheek and heads for the door.
Malvineous: I hope to see more of you soon.
Elaine: Don't worry, you will!
She smiles and the two of them hug their goodbyes before she leaves.

While Marcus and sally are occupied, Malvineous goes into another room in order to stay out of their way. The second woman stands in the doorway.
Elaine: You’re not going to leave me alone with them are you?
Malvineous: I’m sorry, what was your name?
Elaine: Elaine.
Malvineous: Well Elaine, is there anything I can get for you?
Elaine: No, I’m fine, thanks.
Malvineous: I’d better steal some of that food before they eat it all and leave nothing for us. Hold on.
Malvineous grabs what he can carry and brings it back into the other room. The two share it while having a pleasant conversation for an hour.

malvineous puts his hand on marcus' shoulder.
malvineous: heheh. marcus, always the ladies' man i see. c'mon, there will be time for falling in love later. right now we need to find a place to stay.
the ladies point us in the direction of the main colony where a cheap apartment can be found to rent. as we leave in that direction i exchange a wink with one of the women.

according to the databank files, Giganta was terraformed years ago and then abandoned. when it was rediscovered, they found that in the absense of people, the soil became incredibly fertile and the atmosphere very rich. coupled with reduced gravity, it seemed like the perfect place for people to indulge in a life of satisfaction and excess. soon it began to be colonized by humans from around the galaxy who wanted nothing more than to eat the plentiful food, breathe the clean air, and relax in comfort. this was the place we needed to be, and we all knew it.