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As healthy as nuts are, they have something in common with the more dubious snack options: It's hard to eat just one, or just one handful, which is the recommended portion size. You may park yourself next to the bowl of mixed nuts at a party, thinking you're just going to healthfully nibble the night away, and before you know it, you've consumed 546 calories of almonds (that's the amount in a cup).

Fortunately, though, some types of nuts seem to come with their own alarm that sends you a signal that you've had enough. In a study published in the September issue of the journal Appetite, students who were constantly offered pistachios in the shell consumed 22 percent fewer nuts when the researchers left the bowls of discarded shells on their desks than when they took them away. The researchers think the shells acted as "visual cues" that reminded the students how many nuts they'd already eaten.

This study made us think of boxes of Japanese snacks that contain individually-wrapped serving sizes. It's pretty hard to finish an entire box of soy sauce-flavored crackers when the tiny envelopes keep piling up around you. For almonds and other snacks that don't leave a trace, your best bet is to put a handful in a bag, plate or cup and then hold on to that for a while. Better yet, stick to red pistachios, which not only leave a trail of shells but also stain your fingers a shade we'll call "snack-aholic scarlet."

Read more:
Why you should eat nuts (the list keeps growing!)