Hello. I believe I can be of help to you with this issue.
There are probably a number of ways to construe her behavior. First, when you evaluate how much of her own self-image and esteem are focused on how she looks, you get the impression of someone who has significant inadequacies and fundamentally, doesn't like herself very much, and suffers from low self esteem. She is unable to form and maintain intimate relationships and doesn't quite understand why. So one description of what is happening is that she is Overcompensating for her feelings of inferiority.
I suspect that growing up, you felt she was never really quite able to be a completely altruistic, unselfish person and was not very skilled at being mothering or nurturing. So another word that comes to mind that describes her general emotional and attitudinal status is that she is excessively Narcissistic.
So, your mother may have one or more features of a personality disorder; and such people usually have an admixture of features from several of the disorders. You can Google the following to follow up and perhaps identify meaningful patterns in her interpersonal style: DSM Narcissistic Personality Disorder; DSM Histrionic Personality Disorder
; DSM Borderline Personality Disorder
What you can say is something that will link directly into her narcissism and superficial body image that represents her "self"; thus, it should cause her to pause and think: "Mother, when you say such things [or do this and such...], it doesn't reflect well on your image as a personal trainer. A professional would not say such a thing, even to their own daughter. "What you just did
is really quite undignified for a person in your career position because it hurts people rather than helps". "When you act like that mother, it will certainly cause people to wonder what is really beneath that attractive body".
I hope this information is helpful to you. Let me know if I have overlooked any aspect of your original question.