If clinical descriptions of eating disorders (EDs) are ancient (with Avicenna in the 11th century or Simone Porta or Portio in the 14th century), medical history generally credits the first observations by Lasègue in France (1873) and Gull in England (1874) as the foundational accounts of anorexia nervosa. Initially, these clinicians described the disorder by referring to clinical pictures of hysteria and the presence of depressive symptoms.

From these early descriptions, anorexia was associated with many mental disorders, and the 20th century saw the emergence of numerous explanatory hypotheses—from phenomenological to psychoanalytic, cognitive, or family-based models, extending to neurobiological, endocrine, and genetic approaches.

Although this pathology is highly publicized, eating disorders, particularly anorexia nervosa, remain illnesses whose etiopathogenesis is still poorly understood. Many hypotheses have been proposed depending on researchers’ theoretical orientations, but many were based merely on clinical observations that could not be generalized and sought to isolate a single etiopathogenic cause.

With the 21st century came multidimensional conceptions integrating biological, psychological, and social aspects. Today, clinical research embraces the idea that anorexia is a developmental disorder influenced by multiple factors such as family environment, early learning experiences, eating habits, and personal history. These disorders are thought to emerge from the combination of predisposing factors (personality traits, family and cultural context) activated by triggering or precipitating factors (dieting, social difficulties, grief, stress, puberty) and maintained by perpetuating or reinforcing factors (malnutrition, types of social relationships, self-esteem), thus establishing a vicious cycle (Garner, 1993; Lamas et al., 2012).

These multidimensional models have advanced understanding of eating disorders by aligning more closely with individuals’ life trajectories, though they are complex to test empirically. Most research explores only specific aspects of these comprehensive models.

Over the past 25 years, research on eating disorders has entered a phase that combines various approaches and methodologies, allowing for more rigorous testing of proposed hypotheses.

What Are the Clinical Signs of Anorexia Nervosa?

The core of the disorder lies in the refusal to eat, which must be clearly distinguished from loss of appetite. The refusal is not caused by physical illness or secondary effects of another disorder (such as depression).

Consensus now exists around diagnostic criteria (though debates persist). Two main international classifications are used: the American Diagnostic and Statistical Manual of Mental Disorders (DSM) and the International Classification of Diseases (ICD-10) of the World Health Organization.

The main clinical signs are:

Refusal to maintain body weight at or above a normal level (for age, sex, and height).

Intense fear of gaining weight.

Distorted body image.

According to DSM-IV-TR, anorexia is diagnosed when weight is below 85% of expected normal or when the Body Mass Index (BMI) is ≤ 17.5. In addition, individuals avoid “fattening” foods and often engage in compensatory behaviors such as self-induced vomiting, laxative use, excessive exercise, appetite suppressants, or diuretics.

The DSM-5 (2014) introduced modifications:

The rigid 85% weight threshold was replaced with the broader concept of “significantly low weight.”

Clinicians now consider both the individual’s beliefs about weight gain and observable behaviors used to prevent it.

The previous criterion of amenorrhea (absence of three consecutive menstrual cycles) was removed, as it was not applicable to men, prepubertal girls, postmenopausal women, or those on contraceptives.

Additional important features include:

Low self-esteem, often comparable to that of individuals with social phobia (Eiber et al., 2003).

Excessive physical activity, sometimes lasting up to five hours daily, initially for weight loss but later as a compulsive behavior.

Denial of the disorder or its severity; patients often believe their physical and mental state improves with continued restriction.

Summary of Anorexic Symptoms:
✓ Refusal to maintain normal weight.
✓ Intense fear of gaining weight.
✓ Denial of illness severity.
✓ Distorted body image.
✓ Self-esteem tied to body shape.
✓ Hyperactivity.
✓ Obsessional traits.
✓ Primary or secondary amenorrhea (criterion removed in DSM-5).

What Are the Different Clinical Forms?

Diagnoses can also be based on predominant eating behavior, rather than solely on weight criteria. Thus, the DSM-IV distinguishes two subtypes:

• Restricting type: weight loss achieved primarily through dieting, fasting, or excessive exercise—without binge eating or purging.
• Binge-eating/purging type: regular episodes of binge eating and/or purging (vomiting, laxatives, diuretics, enemas).

However, this distinction is debated, as many patients transition between types over time, and binge episodes are observed in nearly half of anorexic patients. The diagnostic boundaries between anorexia and bulimia are fluid, and shared core features include fear of weight gain and preoccupation with body image.

Some researchers argue for mutually exclusive categories based on distinct psychological and physiological processes (Birmingham et al., 2002; Walsh et al., 2009), while others advocate for a transdiagnostic model (Wade et al., 2009), suggesting shared mechanisms across anorexia, bulimia, and EDNOS—centered on overvaluation of body shape, weight, and control.

Empirical data show that 27–45% of anorexic patients exhibit purging behaviors (Johnson et al., 2002; Fairburn et al., 2007), and 16–50% experience binge episodes (Attia & Roberto, 2009). Between 30–80% of bulimic patients report a past history of anorexia (Birmingham et al., 2002).

A longitudinal perspective may better capture this variability: some patients experience alternating anorexic and bulimic phases, while others maintain one pattern throughout life. Studies such as Anderluh et al. (2009) identify four evolving trajectories—lifelong anorexia, mixed anorexia with purging, bulimia following anorexia, and lifelong bulimia—often linked to childhood obsessive–compulsive and perfectionistic traits. These early traits appear to directly influence later restriction, weight loss, and hyperactivity.