Do you follow the fitness tip and exercise 30 minutes a day, five days a week? Well, a new study published in March 2010 in the Journal of the American Medical Association says that might not be enough to keep off weight gain as you age. Instead, the study recommends 60 minutes a day, every day.

1. Adopt a healthy diet and lifestyle. On the diet, you should eat breakfast, lunch, dinner and two small snacks throughout the day. Besides, if you can corporate 2 day diet in your daily diet, you can keep off your weight in a natural and healthy way. As for exercise, a new study says to beat the midlife bulge, women who eat a normal diet need 60 minutes of moderate exercise to prevent weight gain. If you can't get in a full hour of "moderate" exercise, maybe it's time to up the ante with some "vigorous" exercise. Studies have shown that incremental exercise (steadily building intensity throughout a workout) and exercise intensity (mixing short bursts of working out hard and periods of rest) adds to the number calories burned, which is exactly what you'll need to beat the waistline crisis in your 40s and beyond.

2. How to bump up your workout’s intensity?

Walking. Try using core-balancing shoes like Shape-Ups. Or, add Nordic walking poles into your walk. Also, look for stairs, inclines, hills and varied terrain. You may be able to cut that hour into a bite-size 30 to 45 minutes.

Running. Try speed intervals. Run sprints for 20 seconds, then jog the 40-second recovery. You can cut that run down to about 30 minutes.

Swimming. Use a pull buoy or switch your stroke. If you only swim one stroke, your muscles become very efficient and you'll burn fewer calories. Try going from freestyle crawl to backstroke to butterfly. This circuit will change up the muscle groups and muscle recruitment.

Biking. Wear cycling shoes or install toe cages on your pedals. The added stability, although it may take some time to learn to clip in and out, will allow you to use more hamstring power and build your backside. Now, try out those big hills you've been avoiding and see your workout intensity build.