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Snacking on junk gets boring

One of the ways that scientists are approaching the question of weight control is by looking at what causes people to stop eating. One cause, known as "metabolic satiety," describes the hormonal changes that signal the brain that the stomach is full and eating should stop. Another type of satiety is called "sensory specific satiety," which describes the way that a food you are eating becomes less pleasant or tasty as you continue to eat it. Thus a food with a high sensory specific satiety level is something you might voluntarily stop eating - because you're just not enjoying it as much - before your body tells you that you're full.

Sounds like it might have some use in weight control, right? Eating foods with higher sensory specific satiety levels could mean eating less while still feeling satisfied. Researchers in New Zealand saw this and thought about how this might be applied to snacks (Am J Clin Nutr 2012;95(5):1038-47), since what people choose to snack on can have a big impact on the number of calories they eat each day.

Other studies have shown that less healthy snacks such as chocolate and potato chips have a fairly high level of sensory specific satiety. These studies have been fairly short (less than 4 weeks in length) but seemed to indicate that eating these same snacks on a regular basis did not change that level of satiety. But what about healthier snack options, such as nuts?

The researchers designed a study to compare the levels of sensory specific satiety for three different snacks: nuts (hazelnuts), milk chocolate and potato chips. The study lasted for 12 weeks so that they could also see if the levels of sensory specific satiety for each food changed over time.

One hundred healthy people of normal weight were assigned to one of four groups: nuts, chocolate, potato chips, or nothing (the control group). At the beginning of the study, each participant tasted each of the three snacks, rated them for how much they liked each snack, and responded to questions to determine their personal level of sensory specific satiety of each snack.

Each group received the same daily snack every day for 12 weeks and were instructed to eat all of it each day. Each time they ate their assigned snack they filled out a questionnaire that measured the sensory specific satiety they experienced in response to eating that snack on that particular day.

At the end of the study the participants again tasted each of the three snacks, rated them for how much they liked them, and again determined their personal level of sensory specific satiety for each snack.

The researchers were then able to compare the levels of sensory specific satiety for each snack group as well as how it changed over time for each participant. They found that while the sensory specific satiety decreased (meaning it took more of the food to cause satiety) for all of the snack foods, the nuts' satiety decreased the least. Further, those who ate the chocolate or the potato chips indicated that they did not like them as much as they had twelve weeks before, while those who ate the nuts still enjoyed them about the same.

What this means for you

Eating less-healthy snacks like chocolate or potato chips regularly causes you to need to eat more of them to feel satisfied, even though over time you'll enjoy them less. Nuts (or at least hazelnuts) don't suffer from this effect as much, and you'll still enjoy eating them. Stock up on nuts for snacks. (Which nuts? Pick your favorite. Raw and unsalted are best, followed by lightly salted, then salted, but avoid the ones with coatings of any kind and always choose dry roasted if you don't like them raw.)

First posted: May 2, 2012