So what’s mindless eating?
External cues influence how much we eat.You pour more liquid into a short, wide glass than a tall, skinny glass. You eat 92 percent of anything you serve yourself. You eat 20 percent more food served family style rather than left on a side counter. People eating with one other person eat 30 to 35 percent more than they otherwise would. Having a snack within arm’s reach doubles how much of it you eat.

How can you know all that?
We’ve tested it all empirically. For instance, most people say they eat until their plate or bowl is empty, so we wondered what would happen if the bowl was never empty. We made a soup bowl that continuously refilled through a hole in the bottom attached to a hose from a 6-gallon vat. People with refillable bowls ate an average of 73 percent more soup than people who ate from a regular bowl, yet they didn’t think they had eaten more. They said, “How can I possibly feel full? I have half a bowl of soup left.”

How can this help you control your weight?
Our research has identified the “mindless margin” of eating. Going on a diet and cutting out 1,000 calories a day triggers feelings of hunger and deprivation. But a typical person can cut out 200 to 400 calories a day without noticing the difference. That may not seem like a lot, but if you make three 100-calorie cuts a day, at the end of a year you’ll weigh 30 pounds less. Move your candy dish. Get rid of your short, wide glasses. Use smaller dishes. Make some rules for yourself. Only allow yourself to eat a midmorning doughnut if you’ve already eaten a piece of fruit, which means you probably won’t be hungry for the doughnut. Serve the vegetables family style but not the mac and cheese.

At a restaurant, use the “pick two” strategy. Order a main course and only two of the following: bread, appetizer, dessert, and alcoholic drink. At a reception buffet, follow the “rule of two.” You can have whatever you want, but you have to use the smallest plate and can put only two things on it at one time. Always have something to drink in your hand, because that’s one less hand to eat with. —Brian Wansink,Ph.D.

Dr. Wansink is director of the Food and Brand Laboratory at Cornell University and author of “Mindless Eating” (2007, Bantam Books).