Thank you for using Just Answer. Anytime you have strong emotions attached to a basic need such as eating or drinking it is a problem. You may not meet clinical criteria for an eating disorder, but loosing weight because you feel more in control when not ingesting, is a problem. More likely it is symptomatic of the Borderline Personality Disorder. Since I am assuming you have given up some type of self mutilation through the DBT, this sounds as if another form of self mutilation in a more passive and less noticeable way. The self mutilation usually comes from an inability to express these emotions and allows strong feelings to escape. You may be using food and water as the same type of emotional release or control.
AT five feet and 102 lbs you are not extremely malnourished, but if not addressed it could progress into a much worse scenario.
I would recommend you discuss this with your counselor as soon as possible. It is the secretive nature of BPD that makes it have control over you. Gain control and face your emotions by sharing this information with your counselor. He/she can assist you in learning more techniques to manage these symptoms.
Please let me know if you have other questions. Gina