The cliché about a pregnant woman needing to "eat for two" is quaint -- and misleading.

During the first trimester of pregnancy, a woman doesn't need any additional calories, since her body's energy requirements haven't yet increased. It is during the second trimester that a woman is supposed to eat more -- but only about 300 calories more daily. That's a yogurt with fruit, a few chunks of cheese, or a slice of toast with peanut butter -- all a far cry from the pint of ice cream or the pepperoni pizza depicted in commercials and sit-coms.