Disordered eating behavior is, unsurprisingly, a shared feature among the eating disorders. Over the years, participants in our research program have helped us learn a lot about eating behavior by participating in our laboratory meals. For example, we’ve learned that:
- People with bulimia nervosa eat more food, and a lower proportion of protein, than those without an eating disorder when primed to “let themselves go” in the lab. Under this instruction, people with bulimia nervosa are also more likely to start their meals with dessert and snack items.
- Adults with obesity and binge eating disorder eat more during an episode of binge eating than individuals with obesity who do not have binge eating disorder.
- People with anorexia nervosa consume less than those without an eating disorder, even at the end of intensive treatment, and specifically, restrict fats.
- Those with anorexia nervosa have clearly distinct mealtime behaviors – such as being slow to start eating, nibbling, and picking at food – from those without an eating disorder.
Yet even though we, and others, have been able to capture and learn a lot about disturbances in eating, we still don’t fully understand all the factors that influence disordered eating behavior. Recently, we decided to take a deeper dive into our meal studies data to see if we could learn more about the potential role of anxiety in the eating behavior of people with anorexia nervosa.
Anxiety & Eating Behavior in Anorexia Nervosa: Two Hypotheses
There have been two dominating schools of thought on how anxiety and eating behavior might intersect for people with this eating disorder. The first proposes that greater anxiety prior to eating leads to reduced food intake at a given eating occasion. This model is consistent with explanations of anxiety disorders, in which anxiety-provoking situations (e.g., public speaking) are avoided.
The second theory is that eating a greater number of calories leads to increased anxiety for patients with anorexia nervosa. This in turn leads to eating less at future eating occasions, as a means of seeking to avoid unpleasant levels of anxiety – a mechanism known as negative reinforcement.
Previous studies have shown that level of anxiety before the meal is predictive of intake at the meal – that is to say, higher pre-meal anxiety predicts eating less for people with anorexia nervosa. However, the relationship between food intake and anxiety after the meal remained mysterious to us.
What was our approach?
To address the gap in understanding, we recently completed an investigation that combined data across three of our studies that included a laboratory meal. In these meal studies, participants were invited to eat as much or as little as they liked from a buffet with a wide array of foods. They rated their level of anxiety before and after the meal, using a self-report scale. By combining data across studies, we generated a larger (and therefore, more statistically powerful) sample in which we could compare levels of mealtime anxiety, food intake, and the association between the two.
What did we find?
In total, we had information from 92 females with anorexia nervosa and 78 females without an eating disorder.
- Individuals with anorexia nervosa had greater mealtime anxiety and ate less at the meal as compared to healthy controls.
- Within our patient group, we replicated the finding that more anxiety before the meal predicted lower intake. We also showed that there is no association between pre-meal anxiety and intake for people without an eating disorder.
- There was no relationship between amount eaten at the meal and anxiety after it in either group.
What does it all mean? What are the next steps?
We believe that the lack of association between the amount of food eaten at the meal and post-meal anxiety is important. Sometimes, people with anorexia nervosa describe being driven to restrict their intake as a way to manage difficult emotions, such as anxiety. Yet, our study showed that that eating less did not actually reduce anxiety. This finding may be helpful in encouraging individuals with anorexia nervosa towards more effective, and healthier, coping strategies.
Though we found an association between pre-meal anxiety and food intake amongst patients with anorexia nervosa, future studies are needed to help us learn to whether reducing mealtime anxiety helps people with anorexia nervosa to eat more. Thus far, it has proven difficult to reduce mealtime anxiety in this clinical population. Our findings underscore the value in continuing to explore this possibility, to potentially highlight new avenues for treatment.
You can read more about the study described above here:
Lloyd, E. C., Powell, C., Schebendach, J., Walsh, B. T., Posner, J., & Steinglass, J. E. (2021). Associations between mealtime anxiety and food intake in anorexia nervosa. International Journal of Eating Disorders, 54( 9), 1711– 1716.
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