At first, those 100-calorie snack packs seemed like the answer to our prayers: The same treats we'd always loved, in portion (and guilt!) controlled sizes. How could we go wrong?

The case against 100-calorie packs: Sadly, two recent studies say we most certainly could go wrong. Arizona State researchers found that chronic dieters actually consume more food when it comes in 100-calorie packs. Study participants considered the packs "diet food," and believed that four small packs had fewer calories than one large pack of the same food, when in reality both contained the same amount.

European researchers reported similarly disheartening statistics. When given either a large or a small pack of snacks to eat while they watched television, people tended to eat the smaller pack without much thought while giving careful consideration to the larger pack, often not even opening it. (Before the snacks and TV, participants were weighed, measured, made to look in the mirror and asked about body image and weight concerns.)

The case for 100-calorie packs: The numbers don't all point against 100-calorie packs, though. University of Colorado-Denver researchers gave people the same snacks in both large- and small-sized bags to bring home at different times, and they found that participants ate an average of 120 calories fewer per day when they had the small-sized bags.

So what's the truth? One interesting difference between the first two studies and the third -- the first looked at chronic dieters, while the second studied people who'd been made very aware of their weight and bodies. The third study, though, didn't select participants based on dieting habits or manipulate their mindset in any way. The takeaway, it seems, is that 100-calorie packs are simply snacks in small sizes ... not miracle diet tools or totally harmless treats.

Tell us: What do you think of 100-calorie packs? Do they help you control portions, or are they simply an overpriced marketing tool?