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With bathing suit season upon us it’s time to start crunching. Getting a flat belly or a defined six-pack takes time, so if you want to have the flat sexy abs of Gwen Stefani or the definition of Ryan Reynolds, you had better start now.

“When picking abdominal exercises, variety is important. Avoid repeating the same old routine and make sure you work all the abdominal muscles surrounding your core,” celebrity trainer Robert Brace, creator of the 28 Day Challenge exercise DVD tells Fox411.

Getting a flat belly is a two-part process. Step one is to reduce belly fat.

Interval training is the best way to get results quick. Try getting on a stationary bike. Push as hard as you can for one minute and then rest for 30 seconds. Repeat 8-10 times.

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For men trying to maximize the definition in your six-pack, try using abdominal machines at the gym that allow you to load up on heavier weights. This will increase your testosterone production, build your lean muscle mass and help you burn fat faster. Choose a weight that makes you tired after 8-10 reps.

When using weights for any body part, perform exercises standing, not sitting. This places greater stress on your core leading to improved definition in the abs. Great exercises for this include barbell curls, dumbbell squats and standing overhead press.

Improving your diet also helps. Increasing protein and fiber intake while reducing carbohydrates, fats and sugars is a proven way to lose belly fat; especially when you are stepping up your workout intensity. After interval training, your body is primed to burn your stored body fat to use as energy. Reducing carbohydrates, fats and sugars in your diet maximizes your potential to burn fat in that hard-to-reach midsection.

Now that you’ve prepped the canvas, it is time to paint on the definition. Try these three moves to sculpt your belly into shape.

Toe Touches: Lie on your back with both feet straight up to the ceiling. Reach your arms straight above your head, keeping them horizontal to the floor. Reach up and your touch toes, keeping your arms straight, then slowly return to the starting position. Do this 20 times.

Side Planks: Lie on your side with your feet and shoulders stacked on top of each other. Place your elbow and forearm on the floor and raise your body off the floor so that your body is in one straight line from your heels to your hips to your head. Hold for 30 to 60 seconds.

Reverse Crunches: Lie on your back with your hands by your side and your feet placed on the floor. Bring your knees towards your chest, raising your hips off the floor. Repeat 20 times.

Do this for a month, and then sit down next to Mr. Reynolds or Ms. Stefani, and compare.