A weight maintenance diet reduced bulimic symptoms in adolescent girls
Q Does a weight maintenance diet reduce bulimic symptoms and negative affect in adolescent girls?
randomised controlled trial.
blinded (data collectors and outcome assessors).
Follow up period:
Austin, Texas, USA.
188 girls 14–19 years of age (mean age 16.7 y, 57% white) who had body image concerns were recruited from high schools and a university using direct mailings, flyers, and leaflets.
a healthy weight management intervention (n = 94) or an assessment-only control condition (n = 94). The healthy weight management intervention comprised 3 weekly, 1 hour, small group sessions (6–10 participants) facilitated by a clinical psychologist or graduate student and a research assistant. In session 1, facilitators explained that the intervention would help them to make small permanent lifestyle changes that would allow them to achieve and maintain a healthier body weight (a “healthy” ideal rather than the “thin” ideal). They provided instruction on how to gradually develop a balanced diet and individualise behaviour modification tips to their own eating and exercise habits. Homework was completion of a 3 day food diary and exercise diary. In session 2, group members reviewed their eating and exercise diaries and provided support for each other about problems encountered in achieving behaviour modification goals. Homework included listing 10 personal reasons for pursuing the healthy ideal, and the food and exercise diaries. In session 3, participants discussed problems encountered and shared changes in exercise levels. After 1 week, they were asked to send e-mails to facilitators outlining their progress in making lifestyle changes.
obesity (95th centiles of body mass index for age and sex from nationally representative survey data), bulimic symptoms (average of 7 diagnostic items from Eating Disorder Examination), negative affect (average of three 5 point subscales from the Expanded Form of the Positive and Negative Affect Schedule), healthy eating (average of 4 items assessing eating behaviours), and exercise intensity (quantity × frequency measure).
Patient follow up:
96% (intention to treat analysis with last outcome carried forward for dropouts).
During the 1 year follow up, the risk of onset of obesity was lower in the weight management group than in the control group among initially non-obese participants (n = 162; 1.2% v 11%, relative risk 12%, p = 0.032). The weight management group had greater decreases in bulimic symptoms (p = 0.004) and negative affect (p = 0.017) than the control group and greater increases in healthy eating (p<0.001) and exercise intensity (p<0.001).
A weight maintenance diet reduced bulimic symptoms and negative affect in adolescent girls.
- Janet D Allan, RN, PhD, FAAN
The study by Stice et al, which examined the effects of a weight maintenance diet on bulimic symptoms in adolescent girls, challenges the longstanding belief that dieting increases bulimic symptoms. The findings show that a weight maintenance intervention reduced bulimic symptoms, obesity risk, and weight gain.
The study is methodologically strong, with randomisation of participants, good description of the intervention, blinding of data collectors and outcome assessors, and 1 year follow up data. Use of self reports for healthy eating and exercise intensity as outcome measures limits the researchers’ ability to validate changes. That is, participants receiving a dietary intervention may be more likely to report positive changes than those in the control group.1 Using body mass index as a measure of obesity could be problematic given that some participants were still growing, and we do not have standards for different racial groups.
The results of Stice et al add to a growing body of evidence that counters the dietary restraint theory, which posits that dieting increases the risk of onset of bulimic symptoms. According to the theory, as dieting (viewed as a cognitive activity) fails or is disrupted, individuals become vulnerable to uncontrolled eating. 3 other experimental studies that focused on weight loss concluded that dieting curbed sub-diagnostic levels of bulimic symptoms.2,4 However, these studies focused on dieting interventions rather than healthy eating, which was the focus of the study by Stice et al. So, the question is whether the study by Stice et al is a good test of the restraint theory or if some other mechanism could explain the reduction in bulimic symptoms? One might expect that healthy eating and dieting interventions could have different psychological effects.
For clinicians, the findings suggest that weight maintenance or healthy eating is an effective prevention programme for bulimic symptoms and for weight gain. The brevity of the intervention makes it potentially feasible in busy primary care and school health settings where adolescents receive care. Clinicians in these settings can identify adolescents at high risk and initiate bulimia and obesity prevention programmes. It will be important to consider tailoring clinical interventions, particularly to groups who may be less educated and less motivated.
For correspondence: Dr E Stice, Oregon Research Institute, Eugene, OR, USA.
Source of funding: National Institutes of Health.