Big things come in small packages. And apparently, so do calories.

You probably have a box of them in your cupboard right now – those small little snack-sized bags that contain 100 calories of your favorite cracker, cookie, pretzel or cereal. They’re the perfect way to indulge without overindulging, right? Well, apparently, these snack bags actually fuel one’s desire for snacking – more so than the full-sized snack bags do.

The study – recently published in the Journal of Consumer Research – focused on the food selection and eating behaviors of volunteer participants (though they were under the impression the study was for something else entirely) and was conducted by researchers from the University of Kentucky (Go Wildcats!) Arizona State University (Go Sun Devils!) and the Technical University of London (conducted separately but as an addendum to Kentucky and Arizona State’s collaborative study). Basically, the study attempted to unravel participants’ perceptions of different sizes of food when presented with them.

In one study, participants were put into two groups: one group consisting of people who rarely dieted, the other consisting of people who dieted frequently. The researchers put bags of M&M’s in front of the participants, some of which were regular in size, others in the smaller “fun” sizes often seen in grocery stores around Halloween. Not surprisingly, the regular-sized bags weren’t selected all that much by the group who dieted frequently – or the “restrained” eaters, as the study referred to the group – the reason being that the large bags have more calories and will pack on more weight (or so the researchers’ theorize). But the small bags? Those were selected quite a bit, and by the restrained eaters more often than the “unrestrained” eaters (i.e. the participants that didn’t diet much if at all).

The other study was similar to the first, in that it tested to see how the participants reacted to differing sized bags of snacks, but unlike the first study, these participants were not grouped according to whether or not they dieted. Despite this difference, researchers from the Technical University of London found similar results. For instance, when the researchers presented the participants with a selection of potato chips in various sized bags, the smaller bags were selected more often and seem to pique food cravings more than the larger bags.

On the surface, this study seems counterintuitive: How can bags of smaller size actually cause someone to eat more than bags of larger size? But when you think about it, it makes sense. As the researchers note, the smaller bags are perceived as, well, diet food – foods that really aren’t going to bring about utter ruin to one’s weight loss goals. But had these smaller bags not been there at all, it’s likely that the participants wouldn’t have succumbed to temptation– as the larger bags have more calories, therefore a greater risk of overindulging.

This finding is not unlike what your dad used to do (or still does) when a cake or pie is around. He didn’t want a whole piece, so he just scraped off a teeny-weeny piece from the baked goodie with his forefinger and thumb. Of course, this was the first of many teeny-weeny pieces scraped from the cake or pie that by the time he was done he wound up eating more than he would have had he taken an entire slice!

It’s also not unlike what retail stores often do with their “buy one, get one free” ploys. Sure, it’s nice to get something free, but people often buy that CD or blouse to get the free item – when they probably wouldn’t have bought anything had the “get one free” deal not been in effect.

Advertisers and marketers understand human nature and how best to exploit it. Snacking is fine every now and then, but it’s important to know yourself and when you’re truly hungry. Don’t let clever labels listed on packaging fool you into believing that a 100 calorie pack is somehow “diet” or “healthy.”

Remember, just as in the example of the buy one get one free deal – where we buy something to get something, even though we probably wouldn’t have bought that something in the first place had the “free” deal not been there – 100 calorie packs can trick us into believing we’re hungry when we’re really not.