I think we're hard-wired to believe that bigger equals cheaper. So people feel that it costs nothing to use more. And for most products, you do save money by buying a larger size. Drop Anchor Signs in supermarkets can also encourage people to buy more food. When consumers shop, they anchor on a suggested number to buy and then adjust that up or down, depending on the circumstances.
Most people anchor on one or two, and usually buy one to three of the item.
Include in your shopping list the amount of each item to buy. At restaurants, don't hesitate to ask for a doggie bag. You'll have tomorrow's lunch already made. Offer to share an entree, appetizer, or dessert. You'll save money and calories.