Best Belly All-Around

Slim down your middle faster with this dual routine that tones both your belly and back in one shot. Although some ab exercises can strain your spine--even if you don't feel pain when you do them--these isometric moves, in which you hold a position instead of doing lots of reps, were proven in an exercise lab to firm the midsection with minimal stress to the lower back. Plus, a stronger back improves your posture, giving you an instant tummy tuck. Get started now to see results in 3 weeks.

Stuart McGill, PhD, author of Ultimate Back Fitness and Performance and a professor of spine biomechanics at the University of Waterloo in Canada, developed this workout. abs and back--so you look trimmer from every angle!

Perform the moves in the order listed. Hold each for 10 seconds, bracing your abs (as though a ball were going to hit you in the stomach), but don't hold your breath. Repeat 4 to 8 times. Try the Main Move first. If it's too difficult, do the Make It Easier option. When you can complete 8 reps of the Main Move with ease, progress to the Make It Harder version. Do this 15-minute routine once a day, at least an hour after you wake up, so your muscles are warm.

For Faster Results: Do 30 minutes of cardio, such as walking, jogging, or cycling, most days, with 1 long, 60- to 90-minute workout each week.

Lie with Right knee bent, foot flat on floor, left leg extended, hands under lower back. Lift elbows and inhale deeply. As you exhale, contract abs and curl head, neck, and shoulders to raise shoulder blades a few inches off floor. Hold and lower, including elbows. Do all reps, then switch legs.

Make it easier:  Simply brace abs, hold, then release, keeping head on floor.

Make it harder: Lift extended leg a few inches off floor and hold as you raise and lower upper body. Switch legs and repeat.