In other words, if you eat until you are completely sated, or perhaps over-full, are you likely to delay consuming that same food again? The answer is yes – a tantalizing finding with implications for everyone from food companies focused on super-sizing to parents of picky eaters and anyone regularly tempted with the excesses of American life.
“People have a tendency to overindulge in foods they enjoy, not realizing the effect. This is the argument for moderation, if we needed one,” says Shiv, the Sanwa Bank, Limited, Professor of Marketing at Stanford Graduate School of Business. “You actually take more pleasure in it.”
To study this, the researchers conducted a series of studies, including one in which they asked 134 undergraduate students to sample three flavors of Nut Thin crackers and then choose one to eat. The students were given a specific number of crackers and were asked to rate how much they enjoyed each one after they ate it. The students who ate the larger portion (15 crackers) reported significantly lower enjoyment than those who ate the smaller portion (3 crackers).
These findings replicate previous ones on “sensory-specific satiety”: Each bit of the same food is less pleasant than the one before it. Thus, the bigger the portion, the less enjoyment you get out of the last few bites.
More importantly, participants’ enjoyment of the last cracker (manipulated by portion size) seemed to influence how soon the students wanted to eat the crackers again: Participants who ate a small portion typically opted to receive a giveaway box of Nut Thins sooner than did participants who ate the larger portion.
This research has implications for questions surrounding portion sizes, which have reached unhealthy sizes in the United States. For instance, 96 percent of the main entrees at the 400 largest chain restaurants in the country do not meet the U.S. Department of Agriculture’s (USDA) nutritional recommendations, according to research by Helen W. Wu and Roland Sturm of the Rand Corp. The entrees deliver too many calories for the nutrients they contain.
The new research shows that restaurants and food companies that super-size may be shooting themselves in the foot by reducing the number of times a consumer buys.
“It suggests that large portions may be somewhat detrimental to companies because they extend the amount of time that passes until repeat consumption occurs,” says Garbinsky, a Stanford GSB PhD student and the study’s lead author.
In another experiment, the researchers were able to reset the feeling of satiety. Students in a control group were given sips of juice and then two crackers to eat. Those in a second group were given the same portion of juice and the two crackers, given the distractor task of counting “e’s” in a series of passages, and then given another sip of juice. Those in the second group reported more enjoyment of the juice and wanted an earlier delivery date for a free half-gallon of juice.
The crackers seemed to partially reset the students’ satiety level, enabling them to enjoy the juice again as if they were taking their first sip. With that increased end enjoyment, they were more eager for the juice again.
Parents of picky eaters could keep this lesson to heart, says Shiv. Rather than insisting that your child eat every last bite of broccoli, introduce another taste in the middle of the serving of broccoli, to reset levels of satiety. Next time there’s broccoli on the plate, your youngster may be more willing to eat it again.
Finally, researchers found that when people are consciously aware of the pleasure of eating or drinking, they reported more enjoyment of it. Researchers asked 128 students to drink 8 ounces of grape juice and asked some to rate their enjoyment as they drank.
When they were able to better remember the pleasure of the first taste, they reported enjoying the juice more and were more eager for the grape juice again.
If you keep in mind the pleasure you had with your first sips of wine, you may be able to moderate your consumption by recognizing that overall, you will feel more pleasure if you sip slowly while you eat. Similarly, if you focus on what a kale smoothie tastes like with the first sip, and don’t force yourself to finish the last bits after it has stopped tasting good, you might be more willing to have it again for lunch tomorrow.
The research is important in the field of memory, where academics are engaged in questions about the relationship between time and memory and when our recency bias shows up. For instance, as you make decisions, do you more clearly remember the first piece of information or the last? Or, which do you weigh more in the decision-making process? What if you have many pieces of information to draw from?
The researchers looked at this question in the gustatory domain, says Shiv. Turns out that our last bite, associated with the feeling of over-satiety, matters more than the pure pleasure of the first bite. This suggests that our brains may be incapable of recalling, viscerally, the pleasure of the first bite or sip once its gone, Shiv says. We’re only left with the conscious shadow of the experience. In fact, that’s an area that future research may explore.
“It might be that the brain simply cannot remember,” says Shiv. “Taste is something that is much different.”