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Reseal the bag

In the Dr. Gourmet household we usually have a bag of tortilla chips on hand for when we make Taco Salad for dinner. Unfortunately, the bags our favorite chips come in are just huge - we almost never get through the entire bag before the chips go stale. We've tried folding over the top of the bag and using a rubber band around the whole bag or one of those plastic clips that claims to reseal the bag, but inevitably the chips lose their crunch and sometimes even start to taste rancid (ugh).

Last week my wife brought home a bag of tortilla chips with what in retrospect is an obvious innovation: it's a resealable bag. It does seem like more and more foods are being offered in these resealable bags, leading a group of researchers in Belgium to wonder if those resealable bags might have an effect on how much people eat of what's inside (Appetite 2017;117:143-151). We've seen that people serving themselves with larger spoons eat more and that different sized plates can also affect how much people eat. We've also seen that people will eat less candy when they have to make a little more of an effort to get it, either by having to get up from their desk or simply unwrap the candy.

The team in Belgium performed three related studies. First they surveyed 81 men and women using an online survey tool. They were asked to imagine that they were shopping for groceries when they found themselves on the snack aisle. They were shown a picture of a large (multiple serving) bag of Skittles® and asked to list reasons that they might choose to purchase that bag of Skittles. Half of the images were labeled as resealable bags, while the other half were the standard, non-resealable bags. Followup questions asked the participants to estimate how much of the bag they thought they would eat in one sitting, then in a separate question they were asked how much of the bag they would save for later in the event they were given that bag of Skittles. Many of those who were shown the resealable bag spontaneously mentioned the resealability as part of the reason they would buy that bag: "I can keep them around and take just a couple of pieces from the bag when I feel like it," and "I can indulge just a bit and then stop" were typical responses. Other participants specifically mentioned that the product would remain fresher longer and that the resealability would help them consume in moderation. Overall results from this study suggested that a resealable bag meant that they participants would consume less in one sitting: those shown a resealable bag believed they would consume about 25% of the bag, while those with a non-resealable bag believed they were more likely to consume half the bag in one sitting.

A second study included 79 male and female students who were invited to attend a film screening. As part of the screening they were provided with a beverage and a snack - a bag of jelly beans (the test item). All of the bags of jelly beans were presented already open, but half were resealable and the other half were not. At the end of the film the researchers measured the amount of jelly beans consumed and surveyed the attendees about the film, the theater, and the candies. All but one of those who received the open but resealable bag of candies did notice that the bag was resealable, and further, 90% of those did seal and reseal the bag during the movie. Those who received a resealable bag consumed significantly less candy than those with a non-resealable bag, even though their perception of what was an appropriate amount to eat during the movie didn't seem to be affected by whether the bag could be resealed or not.

A third study of 43 men and women involved providing the participants with a set of four bags of different types of snacks for them to consume over a six-day period. Like the previous two studies, the snacks in question were all unlikely to go stale quickly and included items such as M&M's and gummy bears. The participants kept detailed diaries of when they consumed the snacks and how much they consumed on each snacking occasion. Again, those who received resealable bags ate less overall, snacked less frequently, and on average consumed less every time they opened the bag.

What this means for you

These results might be different if the snack items in question were more likely to go stale if left open, but it's certainly something to keep in mind if you're going to have snack items or foods in multi-serving packages around the house. It does seem that opening and reopening the package helps people manage their intake - so look for resealable packages for your snacks.

First posted: September 6, 2017