Exercises make your abdominal muscles bigger.
Adding more muscle to the body causes us to burn more calories, and this helps to increase our metabolism.
It takes more energy to maintain bigger muscles so you are burning more calories and losing more fat while you rest after the exercises.
Don't forget to combine stomach exercises with correct eating habits to get the best results in the shortest time.
Effective Abs Exercises
Best Upper Abs Exercise : The Basic Crunch
Lie on your back on the floor or on an exercise mat with your hands to the side of your head or crossed on your chest. Keep your knees bent at a 90 degree angle with your feet resting on the floor.
Lift your shoulder blades of the ground as if you are trying to touch your knees with your chest but do not move the legs. Concentrate on lifting using your stomach muscles only.
At the top of the movement contract your ab muscles intensely and then slowly lower your body down. Lightly touch the floor with your shoulder blades and repeat.
Repeat 15-30 times. Breathe out on the way up, in on the way down. Rest a few minutes and do another set of 15-30 repetitions. Try to do 3-4 sets.
If you are a beginner or if this is hard for you, do 10 repetitions for one set and gradually work your way to the recommended amount of repetitions. The same is true for the rest of the exercises on this list
When doing this ab exercise it is important that you don't actually sit up all the way. When you sit up your hip flexors do most of the work and it can be bad for your back.
Best Lower Abs Exercise : The Reverse Crunch
Lie on your back on the floor with your hands behind your head or on the floor by your hips, with your knees bent and your feet lifted six inches above the ground.
Slowly bring your knees toward your chest and lift your butt of the ground. Concentrate on contracting your abs, you should feel your lower abs working after a few repetitions.
Use your abs do not swing your legs to create momentum. slowly lower your legs to the starting position, six inches of the floor.
Repeat 15-30 times. Breathe out on the way up, in on the way down. Rest a few minutes and do another set. Try to do 3-4 sets.
Best Obliques Exercise : The Oblique Crunch
Lie on your back, knees bent, so your left foot is resting flat on the floor. With your right knee bent, place your right foot across your left knee.
Place your left hand at the side of your head and your right hand on the left side of your abdominals or on the floor next to your thigh.
Curl your body up with a twisting movement, bringing your left shoulder toward your right knee. slowly lower your body to the ground.
Repeat 15-30 times. Breathe out on the way up, in on the way down. Rest a few minutes and do another set. Try to do 3-4 sets.
Don't forget to do the same for the other side as well.
Bonus : The Bicycle Exercise
This is a simple and very effective exercise that works all three areas of your stomach simultaneously.
Lie on your back on the floor with your hands behind your head. Slightly bend your knees and bring them in towards the chest and lift the shoulder blades off the ground.
Straighten the left leg out to about a 45-degree angle while simultaneously turning the upper body to the right, bringing the left elbow towards the right knee.
Switch sides, bringing the right elbow towards the left knee. Continue alternating sides in a 'pedaling' motion for 15-30 reps. Rest a few minutes and do another set. Try to do 3-4 sets.
Source: http://www.flatstomachtips.com/flat-stomach-exercises.html