Why is it that some people dip into a bowl of M&Ms or a pint of Ben & Jerry’s Chunky Monkey ice cream or a bag of Frito-Lay potato chips and eat just a little bit, while other people munch away until the container is empty, or close to it?
Most of us would say it’s because the people in the first group have more self-control, or willpower. But that may be only part of the explanation, according to new research from the University of Minnesota’s Carlson School of Management.
When eating unhealthy foods, people with high levels of self-control actually become satiated (experience a drop in their desire for the food) faster than those with low self-control, the U of M study found. And they seem to do this not because of some physiological difference in how their bodies react to food, but simply because they pay more attention to the amount of food they’re eating.
The study also found that when people with low self-control are made to pay attention to the quantity of unhealthy food they’re eating, they, too, report becoming satiated faster.
“When you watch yourself more, you tend to get satiated quicker,” said the study’s lead author, Joseph Redden, an assistant professor of marketing at the Carlson School, in an interview Wednesday. And when you feel satiated, foods — even sweet and other calorie-laden snacks — “are just not as tempting,” he added.
The U of M study included four separate experiments. For all the experiments, the volunteer participants filled out questionnaires that are routinely used by researchers to determine people’s levels of self-control.
In the first experiment 199 undergraduates were each allowed to choose a snack to munch on while watching a short video. Half of them were given a choice between peanuts and raisins (healthy snacks) and the other half were give a choice between M&M’s and Skittles (unhealthy snacks). The amount of each snack was 40 grams, just under the manufacturer’s serving suggestion of 50 grams. This was done to ensure that the volunteers would eat the entire snack.
The study found that those undergraduates with high self-control (as determined by the questionnaire) lost their desire for the unhealthy foods at a faster rate than for the healthy foods. Whether a food was healthy or unhealthy made no difference in how quickly or slowly people with low self-control became satiated, however.
To rule out a solely physiological explanation for those findings, Redden and his co-author, Texas A&M University assistant professor of marketing Kelly Haws, conducted a second experiment in which 154 participants were asked to rate their enjoyment and satiation levels while eating a bowl of graham crackers that were described as being either healthy (“Lean & Fit”) or not.
As in the first experiment, people with higher levels of self-control lost their desire to eat the neutral or “less healthy” crackers faster than the “healthy” crackers. They also lost that desire at a faster rate than the people with low self-control.
For the third experiment, Redden and Haws decided to test their theory that the difference in satiation rates between the high and low self-control groups was because the high self-control people were paying more attention to the amount of food they were eating. They recruited 465 undergraduates to monitor themselves as they ate either a healthy or unhealthy snack by counting how many times they swallowed. (The students kept track of their swallows with the clickers used in baseball to count pitches.)
“Sure enough,” said Redden, “we found that when we did that the low self-control people looked a lot more like the high self-control people.”
In the fourth experiment, Redden and Haws gave 228 undergraduate volunteers access to full portions of their chosen snack as the students performed unrelated tasks. After 20 minutes, the snacks were removed and participants were asked various questions about their eating of the food. This experiment confirmed the findings from the earlier ones, particularly the finding that how quickly people become “full” and stop nibbling on various foods depends greatly on how much attention they’re paying to what they’re eating.
Watch what you eat
This study, like all studies, has limitations. It involved only undergraduate students, for example, and the types of foods tested were limited.
Still, the results of these experiments may be good news for anybody who struggles with overeating. “Monitoring the quantity you eat can actually help enable self-control,” said Redden.
Be particularly watchful in highly distracting situations, such as when you’re plopped in front of your TV set, he added.
“Watching TV is a bad idea with an unhealthy food,” said Redden, “but maybe it’s a good thing with a healthy food.”