Yes this is true, I mean if she wasn't sure about that idea in the first place that sure is concernin and not helping to see how it really helps her.
BUT if she wasn't sure or didn't know what it was gonna imply she should have etheir asked more question about it or not starting to do it at all. I know elite athletes all have a big team surrounding them but they have (or should have) the final word! I don't think it's worrying whatsoever since she's still in a very healthy shape and as people as mentionned she's putting some muscle weight back on which was (or should have been) in the whole process.
Put yourself in Ana's shoes.
She is desperate to find a new coach after several failed attempts.
She finally get someone who is willing o accept Ana's conditions.
This coach convinces her what she has to do to be successful, and Ana accepts.
I presume she does not know enough about fitness and nutrition to know the right question to ask about the process and possible side effects or body image issues.
As you said, she looks healthy so there is nothing to worry about.
As to people saying she has put on weight, I think there is a difference of opinion.
Some posters, including myself ( and ESPN commentators, not that they are authority in this sort things) thinks she has lost weight since Wimbledon.
I don't even want to address posters who stated that she was overweight she she won RG. That is ridiculous