People are people. They like beauty. I appreciate that you're admitting you're worrying about her figure (assuming you also love her). Although love cannot prevail on such things, those are important facts.
Bro, even though, she has started her dancing again, don't expect significant results in short term. Female & male bodies may functioning differently. Nevertheless, I will tell something I've learned. For years, since I was little boy, I'v been fat. At the beginning of year 2011, I was about 90Kgs. Considering my height & all, that was too much. Although I had this thought in my mind to maintain my body well, untill March, 2011 it didn't work. That month, I began to jogging with few of my friends early in da morning for few months. Then I joined with them to do some workout at a friend's home. We could do it for just few months. But, it really helped me. We couldn't continue either of things, because of jobs & other problems. But, I didn't stop jogging. 'Coz, I had realized one thing. "You do it or not, it's for yourself". So, I've been jogging, at least 10-12 days per month, 5-8Kms. I'm very happy to tell you, last 3rd I checked my weight. It was 66Kgs. That means, I could lost about 23Kgs since March, 2011. I'm telling you these details, 'coz I think that will help you & your gf to get inspired.
& you need to control what you take in. That's important, as much as you do exercises & all other stuff. Drink water. If you can, check the weight (& blood sugar - fasting test, obesity can leads to type 2 diabetes) like monthly, it will help you to monitor & maintain your body. I've been doing that. & I've saved that data. So, when I see the improvement, it makes me happy & motivates me. That's really helpful.
kanne nathuwa inna eka newei 
