The New Numbers to Live By

1...the number of dress sizes you can drop by gaining—yes, gaining!—3 to 4 pounds
If those pounds are muscle, not fat, you lose inches, even as the number on the scale is a bit higher. Why? Because not only does denser muscle tissue take up less space, but the number of calories incinerated by a body with lots of lean muscle is a wee bit higher than if the persons weight is made up of fat, which means you may lose a bit more fat in the bargain. Experts suggest working out with weights or using your own weight as resistance two days a week (on top of your cardio) to reach that 3 to 4 pound goal.

1...the maximum number of times you should weigh yourself each day
Your scale is the ultimate frenemy. When it likes you, youre elated. But when it doesnt—like after a night of too much Chinese food or a few weeks of skipping the gym—it has the power to make you feel not so great. Thats why Adrienne Ressler, a body-image specialist with the Renfrew Center Foundation in Philadelphia, advises women to step on the scale no more than once a day, and preferably less often. “Weight doesn't shift much in such a short time,” she says. for many women, weighing more than once a day can be counterproductive—not to mention crazy-making. If seeing an extra pound or two makes you preoccupied with food or your body, it may be time to stash your scale in the closet for a while.

3...the number of packets of artificial sweeteners youre OK to have daily
Artificial sweeteners let calorie-conscious women (not to mention diabetics) enjoy a wider selection of food choices. Still, questions about the safety of aspartame and other sweeteners persist, which worries many women. “Based on the preponderance of evidence, these things are safe,” says Elisa Zied, RD, author of Nutrition at Your Fingertips, but to be cautious, she advises moderation. By that she means, dont stir several packets in your coffee plus eat a diet yogurt and drink diet soda. “A couple of packets or a couple of diet sodas a day probably isnt going to hurt,” she says.

Heather Weston

How much is too little?
6...hours of sleep

In the past eight years, the number of Americans clocking fewer than six hours of shut-eye a night leapt from 13 to 20 percent. And nearly a third of us are losing even more zzzs over financial concerns, according to a 2009 National Sleep Foundation poll. Sleep-deprived women often find that their work—and workouts—suffer, and theyre more prone to driving drowsy (as dangerous as drunk driving!). They may find their weight creeping up, too. Lack of sleep causes a rise in the level of the hormone ghrelin, which increases the desire for food, and a decrease in the level of leptin, the bodys appetite suppressant.

Most adults need 7 to 8 hours of sleep a night. If you allot the time but cant fall asleep, first check your prebedtime diet and exercise habits. (For instance, besides avoiding caffeine and alcohol, dont work out within three hours of bedtime.) If youre still having shut-eye problems, see your doctor to check for any underlying medical conditions that may be keeping you up.

Watch Senior Food and Nutrition Editor Frances Largeman-Roth, RD, talk about numbers to live by on the CBS Early Show.