A fellow IPer here --
:hugs:
You know from your own experience that when you were ready to address your weight and health issues, you made the choice. You understood what it would take and what you would give up (time, food, money). You took action. It doesn't sound as if your daughter is in the same frame of mind.
I was once a lost, unhappy early-twenty-something. I speak from experience that one of the best things you can do for your daughter is to support her to make a plan for her life and support her to take action on that plan. And by support, I don't mean money -- I mean encouragement, coaching, holding her accountable, and making sure she has someone in her life to kick her butt when she needs it. It's probably not appropriate at this stage in your relationship for you to be the butt kicker. In my opinion, assisting her with the costs of the first month or two of counseling or of prescription anti-depressants would be a generous, supportive parental gesture. Buying product for her -- official or alternative -- is unlikely to result in improvements in her health, her life, and your relationship with her.
Ask her
- what she wants
- what she thinks she can do about it
- what she's willing to do about it
- what she's going to do about it, and when she's going to do it, and when she's going to let you know that she's done it.
What she needs is a sense of her own power and ability to address the sources of her unhappiness. And that's a gift that keeps on giving as long as the first gift you gave her -- her life!