Easy moves for a trimmer, slimmer core

there's no need to buy fancy exercise equipment to get a trimmer tummy. You have just what you need in your own home-a towel! Using a towel for each of these moves helps in multiple ways: It adds resistance, which helps you build muscle and burn more calories; it engages and strengthens your core (your waist, abs and back muscles); and it helps improve your posture, since holding the towel forces you to sit up straight and use good form. Do this workout at least three or four times a week (it'll take about 15 minutes) and you should see results in four weeks.
Grab a small to medium-size towel (in these photos I'm using one from my kitchen) and you're ready to go!

1 Ab Sit-Backab-sit-back

WORKS ABDOMINALS, LOWER BACK

A Sit up straight, holding the towel taut with both hands, arms and legs out in front and feet flexed.
B Slowly roll your upper body back about 45 degrees, contracting your abs and keeping the towel in front of you. Hold for 5 seconds, then return to position A. Do 10 reps.

2 Bicyclebicycle

WORKS ASS, BUTT, THIGHS

Lie on your back with legs straight out and towel in hand. Lift shoulders and legs a few inches off ground, bending left leg in toward chest and placing towel over upper shin. Keep other leg straight. Toes pointed. Hold for a few seconds, then switch legs. Gradually try to switch from one leg to the other in one fluid motion. Alternate sides and do two sets of 30.

3 Pelvic Liftspelvic-lifts

WORKS LOWER ASS, LOWER BACK, THIGHS

Lie on your back with knees bent and put towel between knees, squeezing thighs together to hold it in place. Your arms should be at your sides, palms flat and facing down. Squeeze legs together and lift butt and lower back off ground, raising your legs toward ceiling, keeping abs tight and knees bent. Lower back down. Repeat for two sets of 15.

4 Side Slimmerside-slimmer

WORKS BACK, ABS, WAIST

A Sit holding towel taut, arms straight out in front of you, knees bent. With toes on the floor, heels lifted, twist upper body to your right, bringing the towel down by your hips.
B Bring towel over knees to your left. Keep alternating side to side for 30 seconds.

5 Leg Stretchleg-stretch

STRETCHES GLUTES, CALVES, HAMSTRINGS

Sit with right leg straight out in front of you, left leg bent with left foot touching right thigh. Loop the towel around top of right foot and make sure back is straight. Hold this stretch for 30 seconds. Then repeat on the left side. If this is too easy, bend over and reach chest toward leg for added stretch.

6 Relaxing Crunchrelaxing-crunch

STRETCHES ABS, BACK, LEGS

lie on your back, knees bent toward chest. Place towel over shins and gently pull down as you bring knees closer to chest. Hold for 30 seconds, taking deep, slow breaths; repeat.