A popular dieting strategy is to eat less off small plates, a sort of visual trick. Many people scoff at that, but several new studies back it up. They prove that most times it's our eyes -- not our stomachs -- that decide how much we eat. This is crucial to keep in mind these days, when restaurant portions are designed to fill oversized people. The author of these and numerous other studies on how and why we eat is Brian Wansink, PhD, a professor in both the marketing and nutrition departments at University of Illinois, Champaign. In one recent experiment, he asked 76 adults to estimate how much tomato soup they planned to eat from 24-ounce bowls set before them. The majority responded visually: 55% said they would eat until their bowl was empty... another 26% said they would eat until the soup was half gone... only 19% said they would quit when they were no longer hungry. The researchers then divided subjects into two groups and removed the visual cue -- the size of the bowl -- for one group. By secretly refilling their bowls slowly and persistently through tubes in the bottom, the researchers in effect took away the size of the bowl as a way of helping the subject decide how much to eat. After 20 minutes everyone quit eating, at which time the group with refilling bowls had consumed twice the amount that the other group had. However, when asked to rate how full they were, their answers were the same as those in the other group. In other words, the subjects could have consumed half the amount they did and still have experienced the same satisfaction. Dr. Wansink tells me that visual cues influence virtually all of us in determining how much we eat. Many people deny it, but studies repeatedly show that people eat what's in front of them, using an empty plate -- not a full stomach -- to signal them when to stop. Furthermore, people have visual biases based on the tableware itself. We perceive tall, slim glassware as bigger than same-sized short, squat glasses. For one study, a group of teens poured juice into both types of glasses, but assuming the short glasses were smaller, the kids poured -- and drank -- 70% more from them than they did from the tall glasses. Dr. Wansink's advice for smart diners is this: Control portions by deciding before you start how much food you want to consume, and dish up that amount, no more. Use visual biases to your advantage -- drink from tall slim glasses and eat from salad plates to fool your eyes into thinking you're eating more.