Timeline of a Tummy

We do not enter this world with a flat belly, nor do we usually leave with one. And in between, even the sexiest stomach will have its ups and downs thanks to pregnancy, hormonal shifts, and Coffee Heath Bar Crunch. Wherever you are on the timeline, you can exercise your way to a firmer, flatter core.

Teens and 20s
Estrogen is acting like a busy traffic cop, directing fat storage to the breasts, hips, and thighs. The belly, however, is spared. So now's the time to work it. "Belly dancing celebrates the flesh," says Anita-Cristina Calcaterra, one of a joyously gyrating Boston trio known as the Goddess Dancing, who suggests this great move for a strong and sensuous stomach. Begin by standing facing a full-length mirror with legs hip-width apart, knees bent softly, tailbone tucked, and chest lifted. Heart circles: Imagine using your breasts to draw a vertical O in the mirror. First, lift up from your diaphragm. Keeping your hips still, in a continuous motion, slide your chest directly to the left, then down toward your belly button, across to the right side, and back up to where you started. Do for five minutes a day in both directions.

Few bellies obligingly snap back into shape without serious prodding. Discuss exercise with your doctor or midwife: In most cases, you can take gradually longer walks and move on to more vigorous activity after six weeks. Elizabeth Trindade, founder of Strollercize, suggests these waist whittlers to get you started. Do five reps at a time, slowly working up to 50 reps throughout the day for both exercises combined. Couch crunch: Sit at the edge of a sofa with your feet out and on the floor and hands on your stomach. Relax your thighs and turn them slightly outward, then roll back until your bra line just touches the sofa back. Pull in your abdomen and lift one or both feet off the floor. In that position, contract your abs even more as you exhale to a count of 10. Return feet to the floor, sit tall, and relax

Roll away: Stand sideways behind the stroller (occupied, of course) and grasp the handle with your closer hand. Push the stroller away while slightly bending your knees and sticking out your bottom a bit. Pull the stroller back toward you while straightening up. After five reps, repeat with the other arm (both sides equal 10 reps).

As estrogen downshifts, fat is rerouted toward the upper body and waist. Dubbed the menopot by Pamela Peeke, MD, author of Body for Life for Women, the middle-aged pouch differs from the excess visceral abdominal fat that's linked to heart problems, diabetes, and cancer. The only downside of the menopot, she says, is "a little consternation when you're trying to zip up your skirt or pants in the morning." Focused efforts—including regular cardio that pares calories —help flatten it.

Yoga: Under pressure, women often eat more—especially sugary treats, which help quell the stress hormone cortisol. So take up yoga, meditate regularly, or at least learn to breathe deeply (not graze avidly) when the stress ratchets up.

Core work: Lie on your back with your knees bent and feet flat on the floor. Raise the lower legs until parallel to the floor, knees still bent and arms relaxed at your sides, palms down. Without using your hands to press, pull in your abs and lift your hips (it feels like a rocking motion) a few inches off the ground. Do three sets: first, 12 to 20 reps; second, 12 to 15 reps; third, eight to ten reps. Rest a minute between sets.

It won't take a day. It won't take a week. But with a little (okay, a lot of) tender loving exercise—some might call it tough love—your tummy can defy the rise and fall of nature's timeline and stay winningly tight.