The kicker is that you got married (d'oh) I would have advised against such but it's too late. I see three paths from here for you, OP.
1: Get her to lose weight. This can be something very simple as her eating less and eating better foods. I think diet alone is 80% of weight gain/loss--it's extremely important. However, the details are far more in-depth than this point. Such as you having to cook (healthy) meals, she needs to cut out trash food over time (a little bit occasionally is fine, just don't binge on it every fucking day like most people)
Bonus: Exercise. Something as benign as walking every day (say 10m is a good start) improves one's well-being. If you exercise as well, introduce her to all sorts and get her to stick with what isn't bad for her (for example I dislike running but I love just about everything else)
2: Apathy. This is, "stick with it" it's incredibly unlikely she'll change. There's a chance that she'll pull her finger out, sure. But it's very unlikely. This path is just staying as things are. It's easiest in effort, hardest in the mind. And dare I say, an answer you'll hear a lot from weak people.
3: Break it off. This is complex in many ways. Some would argue to not break it off because of the risk involved for you (divorce) and some would argue to not break it off because she was once somebody you dearly loved. Others would argue for breaking it off because she is no longer the person you loved--she has changed dramatically. People gaining weight does much to their mind and it is nearly never a simple matter of "extra fat! she's all bubbly woo~" And break it off on the point that it is eroding and draining you. You have needs and wants, this woman is no longer providing. It seems to be okay (Especially on reddit) for women to break it off for men if they no longer provide (they have sexual issues/aren't fulfilling (she finds someone hotter)) or he has lost his job or had to down-grade his job. Yet it is taboo to suggest that a woman can be unfulfilling and that a legitimate option is to break it off with her.
I can not say much more on the point that I do not know you [OP] at all and you've given very little information. I can only point you to the above and some posts that have already been posted are useful. I will leave with just two things,
First being that I would either do option 1 or 3. First counts on various variables such as how long we've been together, if I still see genuine potential in her to return to how she was and improve her situation to a genuine healthy state. I'd weigh up the differences and I'd be inclined to the third option if the variables were not favoured. Such as, we have not been together for long, I feel as if she's a lost cause, so on. I'd like to think I value my time and other's space. There's no need for me to be around somebody if I don't like them--This is especially for a relationship where you're supposed to be a partnership. Whether it's lust, love, business, interest, curiosity or whatever. It's supposed to be a bond above all others. Why waste that position?
Second being is that you need to think about yourself. This isn't being selfish, however, don't make the overly common pitfall that is selflessness. If you are not happy, how could she [your partner] be in a healthy relationship and therefore be happy?