Lead by example and be there for her. The people around me have seen my success and are trying to do their own thing.
My Dad has started losing weight and has been successful. I haven't given him unsolicited advice, but I am there for him in case he needs me. He's asked me for advice and I just recently bought him a food scale so he can measure portions out
When your friend sees your success she may reach out to you for help/advice. Just be a supportive and open-minded friend!