The best zone for fat loss: on the stationary bike, the display offers a "weight loss" zone and a "cardio" zone. Which should I use? … and more of your questions answered here

Shape, Feb, 2005 by Suzanne Schlosberg

Q The stationary bike at my gym has a heart-rate feature, and the chart on the machine is divided into the "weight loss" zone (lower intensity) and the "cardio fitness" zone (higher intensity). Does this mean exercising in the higher-intensity zone is better for my fitness but not as effective for weight loss?

A Absolutely not. "Those labels are really misleading," says Amy Roberts, Ph.D., an exercise physiologist with San Francisco's Sport and Health Science center. In fact, exercising at higher intensities will do more to help you lose weight because you'll burn more calories. "All exercise is going to result in fat loss," Roberts says. "You just have to exercise longer at low intensities."

The concept of the fat-burning zone (which Roberts calls "a total misnomer") stems from this physiological fact: At lower intensities of exercise, your body's primary fuel source is fat, whereas at higher intensities, you primarily burn glycogen, a form of sugar (carbohydrates) stored in your muscles and liver. However, the fact that you are using higher percentages of fat as fuel when you take it easier does not necessarily mean that you are burning more fat overall. The bottom line: The more calories you burn, the closer you inch toward your weight-loss goals, regardless of which type of fuel your body depends on for energy.

But this doesn't mean you should go all-out every time you ride the bike either. Too much high-intensity exercise can leave you sore and wiped out, not to mention increase your risk of injury. Just ignore those labels on your gym's cardio equipment, Roberts says, and mix up the intensity of your workouts.

Q I've used stability balls at my gym before, but now I work out at home. I bought two different brands of balls online and was disappointed with both. They have little support and deflate almost daily. Can you recommend some gym-quality brands? How often should a ball need pumping up?

A "A good stability ball shouldn't need to be refilled more than once every couple of weeks," says Linda Shelton, Shape's fitness director, who recommends balls sold through resistaball.com, spriproducts.com and ball dynamics.com. "Keep in mind that the firmer the ball is, the more challenging your workout will be because it requires more stability on your part to keep from rolling off," Shelton adds. You can control the ball's firmness somewhat by over- or underinflating; if you're a beginner or using the ball just for stretching, you may want to underinflate for a softer ball.

Q How long should my cardio sessions be? I've read many conflicting articles--some say a 30-minute workout is enough, while others say you need to do 60 minutes to see results. I am 10 pounds overweight, and my exercise schedule consists of walking 30 minutes a day four times a week. Am I wasting my time?

A No way! "It's commendable to get in 30 minutes four times a week," says Albuquerque, N.M., exercise physiologist Mary Jayne Johnson, Ph.D., regional health and fitness manager for Wellbridge, a national health-club chain. However, if you're aiming to lose weight and you've been exercising for at least a couple of months, you may need to increase the length of your sessions, boost your intensity and/or try to incorporate more activity into other parts of your day.

Given that different organizations offer different recommendations, it's no wonder you're confused, Johnson says. The U.S. Surgeon General and the American College of Sports Medicine recommend at least 30 minutes of moderate cardiovascular activity on most days of the week. On the other hand, the National Academies' Institute of Medicine, a scientific advisory panel to the federal government, recommends 60 minutes of moderately intense physical activity per day.

But the two recommendations aren't as far apart as they might seem. The Surgeon General's 30-minute recommendation applies to sedentary people; that's the minimum amount of exercise considered necessary to reduce an inactive person's risk of heart disease, diabetes and other serious conditions. The Surgeon General does note that for weight loss and prevention of weight gain, more than 30 minutes may be necessary.

That's essentially what the Institute of Medicine is saying with its 60-minute recommendation, which focuses on optimal, rather than minimum, standards. This guideline has been criticized by experts who worry that 60 minutes sounds too daunting to many people and may discourage them from exercising at all, Johnson says: "When some people hear 60 minutes, they panic and think, 'How will I ever do that?

If you can't fit in 60 minutes, aim to boost your calorie burn by walking faster, mixing in short bursts of running and/or walking uphill. "Intensity matters a lot," Johnson says. Johnson also emphasizes that you needn't do all your exercise in one shot, either. Taking four 10-minute walks throughout your day is just as effective for weight loss as walking for 40 minutes consecutively.

Q How can I find a personal trainer without joining a gym? I have a great home gym, and I would like help getting started on a program.