CityOfAngels

Only bring it up if she brings it up. As much as you love her, "encouragement" is often construed as nagging, and can negatively affect her self-esteem. Because of this, make it seem like you're only interested in her losing weight because SHE's interested in losing weight. Recommend she see a nutritionist. I'll tell you right now the nutritionist will tell her to completely stop drinking soda, and if she HAS to drink soda, drink diet soda. The reason being is liquids don't get you full like solids, so you can drink to your heart's content and still be hungry. But one can of soda has slightly less calories than a donut. If she's drinking lots of sodas (out of the 2-liter; lots of refills in restaurants, etc.), she's pretty much eating lots of donuts as far as calories go.

I, personally, switched to diet soda this year after seeing a nutritionist. I don't know how much weight I've lost, but it is a considerable amount; and that's on my temporary hiatus from playing basketball. I can only imagine how much weight I'd be losing if I was still playing basketball every day.

One other thing the nutritionist told me that comes to mind is to make sure that half of all of your meals are vegetables.

Just make sure you give her advice in a loving, caring, and understanding way; and make sure she knows that it's not something you're dwelling on, but rather something you've noticed is bothering HER, and that you love her so much you want to help her be happy with herself, any way you can.

Edit: Oh yeah one more thing that is kinda obvious but the nutritionist told me anyways: Drink lots of water. Lay off ANY liquids with calories; not just soda. That means juice must be had in moderation, too.