is diet advice speech protected by the 1st Amendment?

[DaleCooper]

You don't have to be a doctor to know what is and isn't healthy to eat. One of the ways that Americans have rewritten reality in order to accommodate the feelings of fat people is convincing everybody that eating healthy is rocket science. It isn't.

Now, if this woman is mixing the diet advice with medical advice that only a licensed practitioner should give, like for example telling people that eating veggies is a replacement for taking their medications, then she should be in trouble. But if she's just coaching people on how to eat carrots instead of triple cheeseburgers then she should have every right to run her business.