Eating Disorders and Borderline Personality Disorder: Between Over-diagnosis and Clinical Reality

Introduction: Untangling the Diagnostic Web

The co-occurrence between eating disorders and borderline personality disorder (BPD) represents one of the most complex diagnostic challenges in modern psychiatry. With BPD prevalence reaching 25-30% in people suffering from EDs (versus 1-2% in the general population), this association raises crucial questions: are these two distinct disorders reinforcing each other, or different expressions of the same fundamental distress?

This question goes beyond academic debate. In my Paris practice, I regularly meet people bearing this double diagnostic label, often hastily applied, sometimes wrongly, with major therapeutic consequences. The BPD diagnosis can open valuable therapeutic doors, but it can also stigmatize, exclude from certain care, and lock into a pathological identity difficult to overcome.

Navigating between over-diagnosis - particularly frequent in women presenting "difficult" behaviors - and under-diagnosis - notably in men or people from privileged backgrounds - requires clinical finesse and constant questioning of our diagnostic assumptions.

Borderline Disorder: Beyond the Clichés

Understanding Central Emotional Dysregulation

BPD is characterized above all by massive emotional dysregulation. Emotions are experienced with tenfold intensity, skyrocket in seconds, and take hours or even days to come down. This permanent emotional storm exhausts and terrorizes those who experience it.

In this context, eating behaviors become desperate attempts at regulation. Restriction provides a sense of control facing emotional chaos. Binge episodes offer temporary relief through the numbness they provide. Vomiting allows brutal but effective emotional discharge. The ED thus becomes an emotional survival tool, imperfect but accessible.

This regulatory function explains why EDs in borderline individuals are often more unstable, alternating severe restriction and massive crises, anorexia and bulimia, in a waltz following emotional roller coasters. Weight can vary dramatically, reflecting inner instability.

Fragmented Identity and the Body as Battlefield

BPD involves profound identity disturbance. "Who am I?" becomes a torturing question without stable answer. Self-image fluctuates dramatically: genius one day, waste the next, without nuance or continuity.

The ED offers a substitute identity. "I am anorexic" or "I am bulimic" becomes an anchor point in identity chaos. The eating disorder, however painful, offers coherence, rules, community. It becomes the thread giving meaning to fragmented existence.

The body becomes the terrain where this identity battle plays out. Self-harm, frequent in BPD (70% of cases), can accompany self-punitive eating behaviors. The body is alternately sanctuary to protect (restriction) and enemy to destroy (binges, purges), reflecting fundamental ambivalence toward oneself.

Abandonment: Central Terror and Pathological Organizer

Fear of Abandonment as Behavioral Driver

Terror of abandonment, real or imagined, organizes borderline psychic life. This fear is not simple anxiety but existential terror: being abandoned equals ceasing to exist. This primal anguish profoundly influences eating behaviors.

The ED can become a means to retain attention and care. Worry caused by thinness or crises guarantees a form of presence, even negative. "At least when I'm sick, people take care of me" becomes an unconscious but powerful logic. The eating disorder maintains a link, pathological but reassuring.

Paradoxically, the ED can also serve to test bonds: "Will they still love me if I become fat/thin/difficult?". These relational tests, exhausting for those around, often create what they seek to avoid: rejection and abandonment, confirming worst fears and reinforcing pathological behaviors.

Unstable Relationships and Their Impact on Eating

Interpersonal relationships in BPD oscillate between idealization and devaluation. This relational instability directly impacts eating behaviors. In relational idealization phase, the person may "feel better", eat more normally. In devaluation or breakup phase, symptoms explode.

This dependence of eating state on relationships poses major therapeutic challenges. Therapeutic transference becomes central: therapist idealization ("only you can save me") alternating with devaluation ("you understand nothing"). These transferential movements often accompany significant symptomatic fluctuations.

The Question of Over-diagnosis: Biases and Prejudices

Gender Biases in Diagnosis

BPD is diagnosed 3 times more often in women, but does this difference reflect epidemiological reality or diagnostic biases? Intense emotional behaviors are more easily pathologized in women. Male anger will be seen as assertion, female anger as "borderline hysteria".

In EDs, these biases amplify. A woman presenting chaotic eating behaviors and intense emotions will quickly be labeled borderline. A man presenting the same symptoms will rather be diagnosed bipolar or simply "stressed". This difference is not trivial: it determines proposed treatments and anticipated prognosis.

Diagnostic Stigmatization and Its Consequences

The BPD diagnosis carries significant stigmatizing charge, even among professionals. "Borderline patient" evokes manipulation, difficulty, team exhaustion. This stigmatization influences care quality: less empathy, more distance, negative anticipation creating self-fulfilling prophecies.

In the ED context, this double stigmatization (ED + BPD) can lead to exclusion from certain care programs ("too complex"), refusal by certain therapists ("I don't take borderlines"), excessive psychiatrization of behaviors that could be understood otherwise.

Clinical Reality: When Diagnosis Is Relevant

Essential Differential Criteria

Distinguishing an ED with emotional dysregulation from genuine BPD + ED requires fine evaluation:

Chronology: BPD generally emerges in adolescence with unstable relational and identity patterns preceding the ED. If relational difficulties only appear with the ED, the BPD diagnosis is questionable.

Stability in remission: During ED remission periods, do borderline traits persist? If emotional dysregulation disappears with eating normalization, it's probably effects of the ED alone.

Relational patterns: Does instability affect all relational domains or only those linked to the ED? Authentic BPD affects all relationships, not just those centered on food.

Differentiated Therapeutic Approach

When BPD diagnosis is confirmed, the therapeutic approach must adapt:

Dialectical Behavior Therapy (DBT): Specifically developed for BPD, it teaches emotional regulation skills, distress tolerance, interpersonal effectiveness. In the ED context, these skills progressively replace dysfunctional eating behaviors.

Attachment work: Explore and repair early attachment wounds, often at the origin of BPD. Create a stable and predictable therapeutic relationship as secure base to explore abandonment terrors.

Integrative approach: Not treating ED and BPD separately but understanding their interweaving. Eating behaviors as borderline strategies, borderline traits as ED maintenance factors.

Toward a Nuanced and Personalized Approach

In my Paris practice, I adopt a cautious and nuanced approach. Rather than quickly applying a diagnostic label, I explore with the person their relational patterns, developmental history, emotional regulation strategies. The diagnosis, when made, becomes a shared understanding tool, not a sentence.

What matters is not so much the diagnostic label as the fine understanding of mechanisms at play. Whether difficulties stem from "true" BPD or ED-related dysregulation, the suffering is real and deserves a respectful and adapted approach. The goal remains the same: supporting toward more emotional, relational, and eating stability, respecting each person's rhythm and possibilities.

Living and eating are two sides of the same coin. Lighten your relationship with food and free yourself from what doesn't serve you!