If you can't feel her ribs, its definitely time to lose a few ounces
Green beans are great and make sure you limit treats. The easiest way to lose weight is less food and exercise! Find a dog park you can take her too and let her run around or get her a little backpack and fill it with some change so on her walks, she is doing 'extra' work. Swimming is also a great activity for weight loss. Many cities have dog friendly pools and beaches now, get her a little life jacket and she'll figure out how to doggie paddle!
You can portion out her daily food and then, from her daily portion, grab some of the kibble to use as treats. This way, you know exactly how much she is eating.
Extra weight is super unhealthy. It leads to coronary disease, joint issues and more. Its really important to slim her down ASAP!