let me ask you a question how old are you (no need to answer this is just your own reference point) and how long has this alter been there inside you? then think about how all that time that they have been with you and have ate this way...

this is what my treatment providers would have me do each time I encountered knowing there was an alter who I felt needed to change something... their habits, their dressing what ever.....

the bottom line is that each of my dissociative type alters came with their own sense of agency... what that means is they had their own jobs purposes, reasons for being created, what they did and couldnt do, how much control they had and so on.... nothing I could say or do could change this. they were there to do say, eat dress what ever how ever they already were doing so...

let me give you an example ...

all rainy would eat was PB&J and hot chocolate. nothing would change this.. why because it was her sense of agency.

when I was concerned about rainy's eating habits my treatment provider told me she was eating what and how she was meant to be..

she was there since before I was 5 years old and still here so obviously this was not doing her any harm nor me the biological body person. in other words if before I knew about them the alter had survived over 20 years on just PB&J sandwhiches and hot chocolate then they will continue to survive safely on that same diet.

the fact that the biological body was alive and the alters were all still there was proof that the body could survive on just what rainy would eat when rainy was in control, what thelma would eat when thelma was in control and so on and so forth.

my point Raging vortex is that your system is how ever and does what ever that has enabled you to survive. if your alters couldnt live on what they are eating none of you would be here today in order to write your post right DID begins in very early childhood so that means your alter who refuses to eat anything has been there for a majority of your lifetime and here you are still alive and here that alter is still surviving and doing their sense of agency right.

my suggestion is instead of trying to change your alters accept them for who and what they are and how ever they are. just let them continue to do what they were created to do. some may be there to not eat and others may be there to eat everything under the sun. what matters is how ever your system is, is what and how it was able to survive since very early childhood.

you can rest assured that if your alter and you have survived all these years you will continue to survive.