A Pilot Study of Interpersonal Psychotherapy for Preventing Excess Weight Gain in Adolescent Girls At-risk for Obesity

Binge eating disorder (BED) is associated with overweight and obesity.1, 2 Although full-syndrome BED is less common in youth than adults, the prevalence of loss of control (LOC) eating among overweight adolescents is substantial.3 LOC eating is defined as episodes of eating during which loss of control is experienced, regardless of the amount of food consumed. Prevalence estimates for LOC eating range from 6% to 40% in adolescent samples.4-6 Similar to BED in adulthood, even infrequent episodes of LOC eating in youth are associated with psychological distress, greater disturbed eating cognitions, and greater adiposity.3 Binge and LOC eating have been shown to prospectively predict increased weight and fat gain.7-10 These data suggest that LOC eating is a risk factor for excessive weight gain in youth, and may provide an important target for preventive interventions. Another potent risk factor for adult obesity is childhood overweight (body mass index, BMI, kg/m2 ≥ 95th percentile).11 Even youth who are above average weight (BMI ≥ 50th percentile), but not overweight, are at risk for gaining too much weight as they grow.12, 13 Given that few studies demonstrate effective long-term weight loss and maintenance,14 prevention has been suggested as the most important approach to reducing the prevalence of obesity.15 To date, there is a dearth of intervention research in adolescents with binge or LOC eating. Only one study provides preliminary evidence that reducing binge episodes using a modified treatment for BED may impact body weight in youth.16 Since many adults with BED report becoming overweight following, not prior to, binge eating on a regular basis,17, 18 decreasing LOC eating episodes in adolescents may reduce the likelihood of excess weight gain and prevent the onset of adult obesity. A number of psychotherapeutic interventions are effective in the treatment of BED in overweight and obese adults.19 For those effectively treated, weight stability typically ensues.19 Cognitive behavior therapy and interpersonal psychotherapy (IPT), two well-tested treatments for BED, were both developed from therapies designed to treat depression. IPT for BED is based on the assumption that binge eating occurs in response to poor social functioning and consequent negative moods.20 IPT focuses upon improving the interpersonal difficulties, and social deficits21 that may perpetuate LOC eating.22 IPT may be particularly appropriate for adolescents at high-risk for adult obesity19 since heavier youth report teasing, social isolation, and compromised interpersonal functioning.23 Indeed, improving social support has been shown to increase weight loss and assist with weight maintenance in overweight adults24 and children.25 Importantly, IPT has been adapted for the treatment of adolescent depression26 and has been shown to effectively improve interpersonal functioning and negative affect in such youth.27, 28 IPT has also been adapted and studied as a preventive intervention for otherwise healthy adolescents with elevated depressive symptoms.29 We therefore conducted a pilot study of IPT for the prevention of excessive weight gain (IPT-WG) in adolescents at-risk for inappropriate gain by virtue of their current body mass index (BMI, kg/m2). We hypothesized that IPT-WG would be acceptable to adolescent girls. Secondarily, we expected that compared to a standard-of-care health education (HE) program, girls assigned to IPT-WG would be more likely to stabilize or reduce their BMI growth. Because the main purpose of this study was to demonstrate acceptability and feasibility, it was deemed reasonable to recruit girls with and without LOC eating. This would also allow for the examination of possible differential patterns of response to IPT-WG and HE for girls with and without such episodes.