The Five Rules of Flat Abs (Rule #2)

Rule #2

Move your butt
Your booty and your belly are unlikely partners in crime. Here’s why: Over time, sitting around too much renders your glutes practically useless and causes your hip flexors—the muscles that connect your hipbones to your legs—to become stiff. This couch-potato combo tilts your pelvis forward, which increases the arch in your back and puts stress on your spine. From a cosmetic standpoint, it pushes your abdomen out, making even a relatively flat stomach bulge. That means that to lose your gut, you’ve got to work your butt.

The glute bridge march and hip-thigh raise will help you get a stronger behind. Combat tight hip flexors with this stretch: In a lunge position, lower yourself so your back knee is resting on the floor. Push your hips forward, keeping your back upright, until you feel a stretch in the front of the hip. Hold for 10 seconds, relax, and repeat. Switch legs. You can increase the stretch by reaching your arms over your head.