You tear open a bag of pretzels—and before you know it, they're gone. Sound familiar? When we eat from a bag, box, or tub, we keep eating because...there's more to eat. A study published in the journal Obesity found that when a portion of food doubles in size, people eat approximately 80 percent more.
Shop for single-serving packs of everything from popcorn to olives to hummus. A University of Colorado study reported that when people snacked from 100-calorie packs rather than regular-size containers, they consumed about 120 fewer calories per day.