I think and advise that ADF or any other form of IF works so much better in combination with LCHF - without counting anything.
She is 23% body fat which (for a young lady) is in the same (athletic) band as my 14%, being a 70-year-old male.
She "sussed it out" and started off with ADF and used 4:3 later. You can, of course, use "proper IF" 5:2 - eating nothing two days a week ¿in combination with e.g. IF 16:8 on other days?