Targeted prevention of excess weight gain and eating disorders in high-risk adolescent girls: a randomized controlled trial

Abstract

Background: The high prevalence and incidence of obesity and eating disorders in US adolescent girls are serious health problems. Because of the shared risk factors for obesity and eating disorders, a targeted prevention of both conditions is a priority.

Objective: We determined whether an adapted interpersonal psychotherapy prevention program is more efficacious for reducing excess weight gain and worsening disordered eating than health education in adolescent girls at high risk of obesity and eating disorders.

Design: A parallel-group, randomized controlled trial was conducted between September 2008 and January 2013 in a university-based laboratory and a federal research hospital. The study included 113 adolescent (12-17-y-old) girls deemed at high risk of adult obesity and eating disorders because of a body mass index (BMI) between the 75th and 97th percentiles and reports of episodes of a loss of control over their eating. Girls were randomly assigned to participate in an adapted interpersonal psychotherapy or a health-education group program for 12 weekly 90-min group sessions. Follow-up assessments occurred immediately after group programs and at 6 and 12 mo.

Results: Participation in both conditions was associated with decreases in expected BMI gain, age-adjusted BMI metrics, the percentage of fat by using dual-energy X-ray absorptiometry, symptoms of depression and anxiety, and the frequency of loss-of-control eating over 12 mo of follow-up (Ps < 0.001) with no group difference. In follow-up analyses, interpersonal psychotherapy was more efficacious than health education at reducing objective binge eating at the 12-mo follow-up (P < 0.05).

Conclusions: The intervention with adolescent girls with loss-of-control eating is associated with lower age-adjusted BMI and percentage of adiposity as well as improved mood symptoms over 1 y. Interpersonal psychotherapy further reduced objective binge eating. Additional research is needed to elucidate the mechanisms by which physical and psychological improvements were observed. This trial was registered at clinicaltrials.gov as NCT00680979.

FIGURE 1.

Study participant flow.

FIGURE 2.

Linear mixed models with repeated measures with the use of maximum-likelihood estimation were used to examine mean (±SE) changes in actual compared with expected BMI gain (P-group = 0.94, P-interval < 0.001, P-group × interval = 0.50) (A), BMI z score (P-group = 0.91, P-interval = 0.003, P-group × interval = 0.91) (B), BMI percentile (P-group = 0.91, P-interval < 0.001, P-group × interval = 0.96) (C), and the percentage fat mass (P-group = 0.90, P-interval = 0.01, P-group × interval = 0.85) (D) over the course of the study by group assignment.

FIGURE 3.

Linear mixed models with repeated measures with the use of maximum-likelihood estimation were used to examine mean (±SE) changes in LOC-eating episodes in the past 3 mo (P-group = 0.03, P-interval < 0.001, P-group × interval = 0.35) (A) and classic OBE episodes in the past 3 mo (P-group = 0.02, P-interval < 0.001, P-group × interval = 0.26) (B) over the course of the study by group assignment. Geometric means of disordered eating episodes are displayed. LOC, loss of control; OBE, objective binge eating.

FIGURE 4.

Linear mixed models with repeated measures with the use of maximum-likelihood estimation were used to examine mean (±SE) changes in social adjustment (Social Adjustment Scale; P-group = 0.04, P-interval = 0.54, P-group × interval = 0.74) (A), depressive symptoms (Beck Depression Inventory, Second Version; P-group = 0.23, P-interval < 0.001, P-group × interval = 0.71) (B), and anxiety symptoms (State-Trait Anxiety Inventory for Children-A Trait Version; P-group = 0.11, P-interval < 0.001, P-group × interval = 0.29) (C) over the course of the study by group assignment. For all measures, higher scores were indicative of poorer functioning.