Becoming a consistent, healthy eater has a lot to do with what’s inside our heads – and I’m not just talking about taste buds. I’m always interested in learning what drives our eating habits. The March issue of Fitness Magazine introduced me to the concept of “habituation”. The basic idea is that the more a person is exposed to something, the less appealing it becomes. The article profiled one woman who kept 10 pints of Ben & Jerry’s Cake Batter in her freezer and gave herself permission to eat it at any time. After a few months of giving in to her cravings, it no longer interested her and she eventually lost 50 pounds. Another woman, whose weakness was cookies, allowed herself to indulge and found that she was satisfied after a few. After four days she said, “I realized that they are just cookies and don’t have special power over me.”
What motivates people to overeat and choose “bad” foods can be highly complex and very individual. My parents did not buy much junk food, but I’d spend my allowance on it and sometimes kept a stash at home. In junior high, my lunch money was often used to purchase ice cream bars. I’d eat Halloween candy until I felt queasy, wait for the feeling to subside, then dig in again. During my teenage years I worked at Dairy Queen and a shaved ice stand. I frequently partook of the goods without becoming “habituated” in the slightest. I spent a year and a half at DQ, during which I would swing between unfettered eating and diet soda and small amounts of fat-free yogurt. The shaved ice job only lasted for one summer. There were 20 or so different flavors to play with, and one slow day in August I made myself bowl after bowl until I felt sick.
There had been other times when I’d felt disgusted with myself after eating too much, but something was different this time. I vowed not to have any sugar (fruit was allowed) for two months and I stuck to it. When I started eating sugar again I still overindulged sometimes. I tried longer fasts. I mostly limited my sweet intake to the things that I really wanted, not just the ones that were available. Several years later, I was able to get to the point where I am now. I have special treats (cheesecake! Godiva chocolates!) a few times a year and a little extra dark chocolate every night. Sometimes I’ll eat more than I meant to, but it’s been a long time since I have gorged myself unto nausea. I don’t think that habituation would have been an effective strategy for me, but I wanted to learn more because it has obviously helped some.
Here are summaries of several studies on the subject1:
Specificity, Dishabituation, and Variety: Habituation is very specific and can be undone. When a habituating stimulus of lemon juice was introduced, there was a marked increase in saliva the first and second time, then the response lessened through the 10th trial. At this point, a “dishabituating” agent (lime juice or bitter chocolate) was introduced. The subjects were then re-exposed to the lemon juice and their salivary response returned to what they had been at the outset.
In another study, subjects were exposed to the sight and smell of cheeseburgers then given the opportunity to eat a portion at repeated intervals. After a short bump, the level of response dwindled until a new stimulus (apple pie) was introduced and interest in eating returned to initial levels.
Children who were repeatedly shown a variety of their favorite foods had a slower habituation response than those who only saw one. The study results were consistent whether high or low calorie foods were used. Even a small variation in the food, such as a different pasta shape, is enough to increased the amount consumed.
Distraction: Subjects who were given a complex computer task maintained a stronger response to the lemon juice stimulus than those who were given a simple task or none at all. Correspondingly, other research has suggested that watching television or listening to audiobooks will increase the amount of food consumed in comparison to a meal that it eaten without such distractions. Social settings can lead to similar results.
Obesity and bulimia: The habituation rates of obese children and adults were much slower than those of their thinner peers. Bulimic women showed no evidence of habituation.
Calorie content: Habituation can be independent of calories consumed or stomach content. Studies have shown that exposure to scents, visual cues, and calorically insignificant portions of lemon juice have been observed to affect people’s reaction to food. In one study, there was no difference in salivary response whether eating regular and artificially sweetened gelatin despite a 300 calorie difference.
And this affects me how? There is a limit to what researchers know. These habituation studies are all focused on the short-term and most people can control themselves around the lemon juice bottle. There are also many hormonal, emotional, and physical factors that play into what and how much we eat. Keeping the house stocked with junk food might lead to habituation for some, but could be a bad idea for others. Still, several practical insights can be gathered from this research.
Access to a variety of foods can make things much harder for a person trying to cut their consumption. Buffets, potlucks, the cookie aisle, and variety packs can entice us to overeat. Even after a filling, savory meal, it seems like there is always rooms for a sweet dessert. In our modern society, there is no shortage of food choices. How then can we re-stack the deck? One blogger found success by eating the same foods every day for a week2. I believe that one reason that the women in the Fitness article were successful was that they only allowed themselves unrestricted access to one single thing. Since the treat was allowed, they didn’t feel deprived, but because they only had one choice, they became habituated. On the plus side, the tendency to desire variety can be used to our advantage when it comes to healthy foods. A good strategy might be to allow ourselves very limited kinds of unhealthy foods while partaking in a wide assortment of nutritious ones.
Distracted eating is the norm. How many people haven’t started eating a bag a of chips while engaged in some other task, only to find their hands soon scraping the bottom of the bag while wondering where it all went. There’s a reason jumbo sizes are sold at the movie theaters. Some people have had success by eating meals without any TV, music, conversation, or reading materials. With nothing to focus on but the food, they find satisfaction sooner. It’s not realistic to eat like this most of the time, but it’s a worthy experiment. When I have dessert, if I pay attention, I usually notice that it’s the first few bites that taste the best. Habituation at work? When you do eat in a distracting environment, here’s something to try: serve yourself a measured portion and then put the rest of the food away to avoid mindless munching.
I don’t think there’s a single magic bullet when it comes to eating better, but I hope that some of this information has been helpful. I’d also love to hear what has (or hasn’t) worked for you.