Ten weeks to a yummy tummy

Forget sit-ups - there's only one exercise to master if you want a flat stomach. A perfectly executed curl will give you a stomach like J-Lo's in eight weeks, and that's not even exercising every day. Sports scientists don't recommend old-fashioned sit-ups any more. The best and safest way to work the abdominals is by using the stomach muscles to lift your upper back off the floor towards your middle in a curl, and to lift your hips off the floor, bringing them up to the chest in a reverse curl.

However toned your tummy, you won't want to show it off if your lovely muscles are hidden under a layer of fat. For maximum benefit, you need to eat sensibly, and do an aerobic workout that makes you break out in a sweat - fast walking, cycling, swimming or jogging - for at least 30 minutes three times a week. Also, a strong stomach will help to support your back and lessen the likelihood of aches and pains.

For a flat tummy by July, follow our four-step plan, exercising at least 10 minutes at a time - but every other day, so the muscles can recover. Warm up with five minutes of gentle aerobics (walking, or running on the spot).

You should start to see the results in a week. In a month, there will be a big improvement, and if you keep up the regime for 10 weeks, you'll look and feel magnificent.

Phase One - the basics

BASIC AB CURL: Lie on your back, legs bent, feet flat and hip-width apart. Relax shoulders, and with elbows at right angles to your head, rest your head in your unclasped hands. Press your pelvis towards the floor. Now push it up, feeling it tilt away from the floor so that your back arches. Rock your pelvis gently between these two extremes, and find a central, neutral position. While exhaling, pull your tummy in and up. This will start to lift your shoulders and ribcage off the floor. Go as far as is comfortable, while keeping your tummy flat (if you feel it starting to protrude, stop, make a conscious effort to pull it in, then continue). Return. Do four to eight repetitions to begin with.

OBLIQUE CURL: The obliques help define the waist. Curl as before, twisting the waist and bringing one shoulder towards the opposite knee. Return to start.

UNSUPPORTED CURL: Start with your arms flat by your sides. Exhale and lift, letting your chin drop slightly while moving your arms up in a straight line, aiming above your knees. Return.

AB STRETCH: From the starting position, have one hand behind your head, the other raised and parallel with one thigh. Exhale as you lift up into a curl, reaching your raised arm past your knees. Return. When you can complete two successive sets of six to 16 reps smoothly without resting, you are ready to move on.

Phase Two - increase your strength

REVERSE CURL: Lie flat, with knees up and bent close to your chest, arms flat on the floor beside you. Exhale, pull your tummy in while starting to curl up the lower part of your spine. Use your abdominals to pull your knees forward, not your leg muscles. Uncurl and repeat.

LEG LIFT AND TWIST: Adopt starting position, with left leg extended in the air. Using your abs, pull your right shoulder up, twisting towards left leg. Curl down, and repeat on the other side.

ROLL UP AND CURL: Begin with knees tucked in to chest, and cross your ankles. Exhale and lift, curling your spine to bring your ribcage and knees close together. Lower and repeat.

HEEL LIFT AND REACH: From basic position, curl up and reach your arms towards your knees, parallel with your thighs, lifting your heels as high as possible, keeping your toes pressed against the floor. (This works the calves. If you get cramp, flex your feet.) Return and repeat.

Phase Three - greater challenger, great results

BACKWARDS CURL: Sit on the floor with your knees raised, feet hip-width apart and back straight. Pull in tummy, exhaling smoothly, rounding your spine and rolling more of your buttocks onto the floor. Don't go too far. Return to start.

STRETCH UP AND REACH: From basic position, raise your legs so your knees are over your hips, and your lower legs elevated. Exhale as you lift, stretching arms towards feet. At the same time, straighten legs and push feet towards the ceiling.

THE CRISS-CROSS BICYCLE: From basic position, raise legs and bend knees towards chest at a 45-degree angle. Exhale, lifting upper body off the floor, then twist at the waist to bring right shoulder and elbow towards left knee and bringing the knee down to meet it. Then move the left elbow to the right knee.

Phase Four - final exercise

FIST CURL: Lie on your back, with your feet on the seat of a chair. Exhale as you lift, bringing your arms up with elbows bent and hands in loose fists, as if doing a chest-press. Squeeze your elbows together. Curl down and repeat.

DOUBLE OBLIQUE: From basic position, raise your left leg, keeping knees level. Exhale, pulling abs down and, as you lift, twist from the waist, aiming your right shoulder towards the raised leg. Swing your arms forwards to reach beyond the outside of the raised leg. Curl down and repeat.

SIDE CURLS: Lie in the basic position, with your right leg on a low stool, and your left leg on the floor, loosely bent to the outside. Bring the right side of your torso up a little, then exhale and swing your right arm forward, aiming your right underarm towards your right hip. Repeat. Then do same number of reps to the other side.

Tips for better curling

Move in a smooth, controlled manner.

Let your abs do the work, not your neck. Support your head by using your hands as a cradle.

During curls where the head is not supported, tuck your chin in a little, allowing the neck muscles to work.

Exhale as you lift, and pull your tummy towards your spine and into your ribs.

Don't allow your tummy to stick out.

Nicki Waterman's Flat Stomach Plan - The Ultimate Abdominal Workouts and Diet, Thorsons, £7.99.