Bulimia Nervosa: A Biobehavioral Study (The Eating Disorder Study)

Bulimia nervosa (BN) is a debilitating psychiatric disorder that primarily affects young
women. Empirically supported treatments for BN have been identified but less than half of
treated individuals achieve long-term remission from the disorder, possibly because current
treatment approaches do not sufficiently account for variables that help maintain the
disorder. Psychosocial models of BN emphasize the role of dieting as a proximal cause of
binge eating and purging. Dieting has both psychological and biological facets but existing
models of BN have overwhelmingly focused on its psychological impact. The investigators have
differentiated between a diet-induced long-term energy imbalance (weight suppression (WS), or
the difference between one's highest-ever body weight and current weight) and a short-term
energy imbalance (current dieting to either lose weight or avoid weight gain). Recent
research has shown that WS levels in BN are elevated and that degree of WS predicts the
severity of various BN characteristics and its clinical course. Studies of current dieting
(CD) to lose weight have found that it is associated with reduced binge eating in BN, a
finding that conflicts with prevailing models of the disorder. The proposed research will
examine biological (e.g., energy expenditure, neuroendocrine and appetitive hormones) and
behavioral (e.g., binge eating and purging) correlates of WS and CD in those with BN.
(Relatively few of those with BN report dieting to avoid weight gain but its biological and
behavioral correlates will also be examined.) The project will recruit 132 women (66 at
Drexel University and 66 at Columbia University) meeting provisional Diagnostic and
Statistical Manual-V diagnostic criteria for BN. The investigators will test the hypotheses
that 1) CD and elevated WS will be associated with alterations in biological indices of
metabolism and appetite, 2) WS will predict greater binge eating and purging, and CD will
predict less binge eating, measured using Ecological Momentary Assessment (EMA), and 3)
higher real time ratings of daily food restriction intentions will predict a reduced
probability of binge eating during the same day but an increased probability of binge eating
in subsequent days. Assessments for all participants will include: weight and reported
previous highest weight (to calculate WS), the Eating Disorders Examination, 14 days of EMA
to assess food restriction intentions, binge eating and purging episodes, three 24-hr food
recalls, and resting energy expenditure and metabolic and appetitive hormones (including
complete thyroid panel, leptin, ghrelin, cortisol and estradiol). Participants will be asked
to return 6 months later for follow-up assessments of weight. This study will elucidate how
two common yet largely unexplored types of dieting influence biological and behavioral
variables in patients with BN, which could lead to modifications of prevailing models of BN
and new strategies for improving treatment outcome.

Inclusion Criteria:

- Diagnosis of bulimia nervosa according to the proposed DSM-V criteria

- Either currently receiving eating disorder treatment or actively seeking treatment

- BMI above 18.5 and below 30

- Not experiencing any signs of menopause

- Medically stable as determined by each site's study physician

Exclusion Criteria:

- Change in pharmacological treatment over past 4 weeks

- Currently taking atypical antipsychotic medications

- History of anorexia nervosa within the past year

- Pregnancy

- Currently taking medications that could alter hormone levels or metabolism

- Disorders affecting metabolism or hormone levels

- Non-removal metallic object

- Co-occurring severe mental illness

- At risk for suicide