By: Dr. Fischer
Over the past few weeks, I have found myself surrounded by cookies, alcohol, gingerbread houses, candy, and advertisements for holiday dinners. I’ve also been thinking about what to write about for our PBS blog post on eating disorder research.
As I ate another cookie that someone brought in to work, I realized that it might be helpful to discuss cue reactivity and cravings!
Most humans like the taste of fat and sugar, and our brains have evolved to motivate us to approach foods that are high in fat. You may have learned about dopamine (a neurotransmitter) and the reward system in the brain at some point.
What a lot of people don’t realize is that dopamine doesn’t necessarily give us pleasure, but it does push us to approach things that are high risk/high reward. Getting a surge of dopamine in your brain is like getting a surge of motivation to approach or act. We just often act to get things that are rewarding.
At some point in your life, I’m guessing that you learned that you liked the taste of ice cream or cookies or cheese, all foods that are high in fat and/or sugar. When you eat these types of foods, you may experience a reaction in your brain; a surge of dopamine to areas in your brain that motivate you to act. Eventually, this surge of dopamine gets paired with even the image of food. Imagine coming home from work and seeing a junk mail advertisement for pizza. You may not have even been thinking about pizza, but the image of that food is a cue that sets off a whole host of reactions in your brain and gut. You may end thinking “Pizza sounds really good tonight,” even if you had not thought of pizza all day.
This is called cue reactivity, and craving is that urge to eat or drink or ingest something when you are faced with a cue. That urge may feel really strong because you get a dopamine surge when you view the cue, which really pushes you to act and go get the food or alcohol or drug.
In my research lab, we conduct studies on how stress and other emotions impact binge eating. We’ve been really interested in the past few years on how individual differences in brain activity when faced with food cues or stress influence vulnerability to binge eating. What we have found is that even though a lot of people with binge eating symptoms experience craving at the sight of food (a cue), not everyone experiences craving right before a binge. Some people have really strong reactions in their brain to food cues – their blood flow increases to regions of the brain involved in approach and reward when they see those food cues. Those people might be the ones feeling really strong urges to order pizza when looking at the junk mail. Other people don’t have the same type of reaction in their brain to food pictures.
We’ve found that women with bulimia nervosa who have those strong reactions in their brain to food cues tend to experience increasing levels of craving before binges, and the craving tends to go down following a binge. Women who don’t experience that same type of brain reactivity don’t seem to report craving before binges.
Back to the holiday season – We are surrounded by food cues! And stress! You may be working really hard to eat regular meals, not feel out of control with eating, and then feel as though it is incredibly difficult to manage those things at this time of year. Some people start feeling very self-critical and have judgmental thoughts about themselves. Well, I think it is really hard to feel in control when your brain is pushing you to go get some food every time you turn around at work, or at a family gathering, or at your school. You are probably in an environment during the holiday season which is flooding your brain with dopamine and hence urges to eat. It is the way our brains were designed to push us to get enough fat to survive. Stress reactions also influence reactivity to food cues in some people, so the combination of family stress and being surrounded by food can make it difficult to feel grounded during the holiday season.
Hopefully you can remind yourself that your brain is working the way it is supposed to when you crave food, and not feel as though you are lacking willpower. And, we at PBS (of course) are also hoping that you just eat what you want when you are hungry!
I wish you health and peace of mind during the next few weeks!