The description of her eating habits managed to disgust me, and I'm not exactly a walking stick. But as everyone is saying, it's her body, and her choice. Not everyone wants to try to live to be a centurion. Some people would rather die young while enjoying life than live to an old age fretting about their health. *shrug*
What you might want to do is not be around when she's eating if that bothers you. The only thing I could see you doing is explaining to her that her language is not appropriate for the professional setting. If she doesn't want to fix that, either, then let her. She's only making a fool of herself, not of you.
This lady seems to have enough issues to deal with, without having someone judge and criticise her. Confrontational criticism of her lifestyle will not work. You will only alienate her. The biggest condition of change is called cognitive dissonance. When your mind has two or more conflicting ideas, it causes a lot of psychological discomfort (or dissonance/discord). She is almost certainly aware of what she should be eating/of how much exercise she needs, but her behaviour is the opposite of what she knows to be healthy. So when these two conflicting ideas become strong enough and persistent enough, the internal discomfort can only be relieved by her changing her own behaviour. And of course, it takes time. Recovery is a complex issue and is beset by relapse and recovery. Try and catch her doing something healthy and praise her for it. The gold tooth is her choice and you will have to deal with your own issues over that fact. If you want to help your friend, then finding out about the cycle of change is a good place for you to start. These links will take you to some excellent articles and relatively short reading. I hope this helps.