By Dr. Gary L. Wenk Professor of Psychology and Neuroscience The Ohio State University Click here to read an excerpt from Dr. Wenk's book, Your Brain on Food.
We all know how pleasurable it can be to eat a piece of chocolate. The first time its smooth richness and tasty cocoa touches our tongue, an area of our brain called the medial frontal lobes becomes activated and our brain rewards us for eating such wonderful tasting food. Obviously, we want to have another, then another, and so forth.
As we continue to eat pieces of chocolate, our brain begins to lessen its activation of our pleasure centers, and we feel less drive to have another piece of chocolate. This is the result of habituation, a decreased physiological or behavioral response following repeated stimulation.
For example, when you first put on your shirt, you notice its presence against your skin. After a few minutes, you no longer notice it for the rest of the day. The brain performs this habituation response all of the time with regard to many different types of stimuli, including to what we eat.
Neuroscientists now have a very good idea about which parts of the brain are responsible for this habituation response, and how your imagination can influence it, therefore influencing the way – and how much – you eat. We also understand why it is so important that our brain responds in this manner.
Our brain wants to help us to survive. In order to survive we all are aware that we need to consume a variety of nutrients, including vitamins, fats, carbohydrates, proteins, and so forth. The best way to achieve this balance of nutrients is to eat a variety of different foods. Thus our brain habituates to even the most delicious foods rather quickly in order to encourage us to try different foods.
Simply stated, our brains love smorgasbords and all-you-can-eat cafeterias where there is a large variety of foods. Then our brains reward us for eating as much variety as possible. Sadly, with this guidance from our brain, we tend to consume far too many calories. This is why it is never a good idea to take your brain to these places.
Sometimes, the innate tendency of our brain to become bored with even our most favorite foods can be useful for losing weight; for example, you could decide to only eat one type of food, e.g. meat. Imagine how wonderful you’ll feel on the first few days of your all-protein diet. Your brain is happy and so are you. Then, as the days go by, you notice how unappealing meat, any form of meat, is becoming. As you continue on this one-food diet, you begin to eat less because your chosen food is just not as enjoyable to eat and, naturally, you begin to lose weight. Unfortunately, with these types of diets it is highly unlikely that your body is getting all of the nutrients that are necessary for good health.
Recently, a group of scientists discovered that there is another way to lose weight by taking advantage of our brain’s natural tendency to habituate to foods. Let’s return to that box of chocolates. What if, rather than actually eating a piece of chocolate, you just imagine eating a piece. You recall the memory of the smooth and creamy texture and the balance of sweet and bitter tastes on your tongue and then mentally roll it around inside your mouth. Now imagine yourself having a few more pieces of chocolate, and maybe another.
What neuroscientists have discovered is that your brain can habituate to its own imagination! Then, when given the opportunity to eat a real piece of chocolate you will actually tend to eat about 40% less. That’s an amazing savings of calories.
Habituation is a wonderful mental tool that we have access to anytime we need it. Before you go to that next party or dinner, just imagine yourself eating your favorite food. It’s probably easier and more effective to just imagine only one food at a time. After you become an imagination master, you can try it on an entire class of foods, such as pastries or even alcohol. According to recent research, this simple mental exercise might regularly save you a few hundred calories.
How long should one “practice” imagining eating certain foods prior to acting on this theory?
No practice is necessary. The key feature is that you only need to have had some exposure to that particular food in order to become habituated to it. The effect should work the first time as long as you can adequately recall a sufficient number of features of the tasting experience, i.e. texture, flavor, tartness, viscosity, etc.
Beyond weight loss, which may not come immediately, how can I gauge if habituation is working for me? What is a good tracking mechanism for this?
Weight loss is the best indicator. However, you could estimate how many pieces of chocolate (or cheese or bon-bons) you ate last time you were exposed to the food source, then count how many you’re having after performing the imagination exercise. Obviously, this would tend to bias your estimation, and you might intentionally eat fewer just to feel better about the process. However that’s a good thing because you’d be more vigilant of your diet and also be quantifying your success on day one.
How long is this effective for?
The idea is that a person prepares their mind for an anticipated exposure to a particular food item; you probably have to know that it’s time to prepare yourself and then do so. Thus, the imagination process is not likely to last very long at all. The same is true for habituation process in general.
Can habituation work inversely, so that you can imagine yourself loving healthy foods, thus bringing yourself to want to eat more of that and leave junk food behind?
In theory, no. That would not be habituation by definition. However, possibly a different neural event might underlie that process – it just has not yet been discovered.