Ultimately it will need to be your daughter that decides to lose weight, and it will have to be for her and not for anyone else.

If you have not been on speaking terms for several months I would not recommend bringing that topic up in conversation. Like this post you have made, you will likely just come across as judgmental and will push her away further. Also, I recommend you take the term "foolishness" out of your vocabulary regarding this situation. There are many reasons someone can be morbidly obese, and foolishness is never the correct term to describe these reasons.

Your daughter is probably struggling and needs support, not judgement.