Minutes of the Columbia University Seminar on Appetitive Behavior(#529)Date: March 5th, 2009 Seminar Title: "Bulimia Nervosa: A Consequence of the Obesity Epidemic" Speaker's Name and Affiliation:
Presiding Chair: Harry R. Kissileff, Ph.D. Rapporteur: Kathleen L. Keller, Ph.D. Attendees and their Affiliation:
Summary: (Prepared by the speaker) Body weight has generally been assumed to be relatively unimportant in restrained eaters and in those with BN. However, though most bulimic individuals are in the normal weight range, Russell (1979) initially noted that they previously weighed considerably more. Interestingly, research on restrained eaters, who also are higher than average in weight suppression (highest weight ever ¨C current weight) started at about the same time that BN first emerged. It may be more than coincidental that BN was first identified, and that restrained eating research was initiated, at about the same time that the obesity epidemic was accelerating rapidly (late 1970s-early 1980s). Though restrained eating is currently viewed as an analogue of the processes that can culminate in eating disorders, it appears more likely that restrained eating and dieting in normal weight women represent efforts to reverse or prevent weight gain than they are attempts to get skinny. Research has shown that restrained eaters (as assessed by the Restraint Scale) have higher BMIs than unrestrained eaters and are also more weight suppressed. Research by Stice and colleagues has shown that restrained eaters eat no less than unrestrained eaters in the natural environment and Lowe and colleagues have shown that chronic dieting predicts future weight gain. Restrained eaters also often show biological characteristics that would make them susceptible to future weight gain (e.g., higher free fatty acid levels; reduced leptin levels). There is also evidence that individuals with BN are also prone to overweight; they have a heightened risk for childhood obesity and their parents are more likely to be overweight. They also show high levels of weight suppression (mean weight suppression was found to be 9.6 kg in outpatients and 12.0 kg in residential patients). Weight suppression also predicts accelerated weight gain among both nonclinical individuals and in those with BN and predicts poorer outcome in CBT treatment. Finally, recent evidence indicates that roughly half of BN individuals reach their highest-ever weight after the onset of their disorder, indicating that they often experience very large weight gains as their disorder progresses. As a field, we have 1) over-emphasized the role of undifferentiated "dieting"in BN, 2) largely ignored Russell's initial emphasis on the possible role of weight suppression in the disorder, and 3) under-emphasized the apparent susceptibility of bulimic individuals to weight gain and overweight both before and after the onset of their disorder. In retrospect, it appears that the field "went cognitive"prematurely. Discussion: Q. Has anyone ever done a study in a lab where you asked people to eat as much as they would like (not binge)?
Q. In the 1990s, Heymsfield and colleagues did a study where they used the Minnesota EAT scale and obese people actually scored higher on the "lying"scales and the "wanting to please"scales. Does this relate to what you are talking about?
Q. The study referred to in the question before raises a very important issue. How much does social desirability account for the effects you are seeing?
Q. Did you (or others) define what you meant by the question "are you dieting?"
Q. Are people who say they are dieting typically restrained?
Q. Among those who are dieting and restrained, what % are weight suppressed? Is weight suppression a good predictor of weight gain?
Q. Where would you put people who diet before they go on a trip? Are they "restrained"?
Q. In those data looking at fat oxidation, you'd want to look at the composition of the entire diet (not just response to a meal), right?
Q. Why don't people focus much on the other subscales of the Three Factor Eating Questionnaire, like "disinhibition"and "hunger"?
Q. In relation to Harry's question, most of our studies show that people who are disinhibited have higher body weights, but we haven't found many relationships with hunger.
Q. Even though they are correlated (restraint and disinhibition), some people have one behavior but not the other.
Q. What % of bulimics were formerly overweight?
Q. What is the Y-axis in that graph?
Q. In your data, are there any genetic or physiological markers to differentiate the restrained from the bulimic who wants to lose a lot of weight?
Q. Does restricted eating come before the development of bulimia?
Q. What about current anorexics? How would they end up on this Drive to be Thin Scale? vWe wouldn't be able to assess them with this measure because they are already below 15% of their ideal body weight. Q. Did you look at the actual weight gain over the course of the study?
Q. Is the drive for thinness in bulimia nervosa internal or external?
Q. What % of bulimics are overweight before onset of the disease?
Q. Is the goal in the future to be able to separate people on the TFEQ from those that are restraining to be healthy from those who are doing it to be thin or control their weight?
Q. My understanding is that the TFEQ was developed by Stunkard and Messick using factor analysis of where a number of different behaviors correlated. Has anybody redone these factor analyses to see if the TFEQ still applies?
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