Waiting 20 minutes to feel full is a tip that may work for slimmer women, but those who are heavier may need longer-up to 45 minutes- to feel sated, according to experts at Brookhaven National Laboratory in Upton, New York. After examining people with a body mass index (BMI) ranging from 20 (normal weight) to 29 (borderline obese), researchers found that the higher the BMI, the less likely participants were to feel satisfied when their stomachs were 70 percent full.

"We discovered that when overweight people eat a meal, the part of the brain controlling fullness doesn't respond as strongly as it does in normal-weight people," says Gene-Jack Wang, lead researcher and senior scientist at Brookhaven. Since an overweight woman may need to fill her stomach to 80 or even 85 percent before she's ready to push her plate away, he recommends starting each meal with high-volume, lower-calorie foods such as clear soups, green salads, and fruit, and doubling portions of vegetable side dishes.