Go your own way

DO those “fat-burning” programs on the cardio machines really work? I usually just do my own thing when I work out, but I am tempted to use those programs if you think that it would be more effective in helping me to lose weight.

AMY

Santa Monica

Almost every cardio machine has some type of “fat-burning” program built into it. For people exercising to lose weight, it is tempting to believe these built-in programs provide a secret formula for maximizing weight loss. Unfortunately, it’s not that simple.

Most of these programs guide the user through a workout that focuses on lower-intensity exercise. At lower intensities, the body burns a higher percentage of fat as an energy source; at higher intensities, it burns a lower percentage of fat and a higher percentage of carbohydrates.

However, at lower intensities, the body burns fewer calories overall. As an example:

For a woman who power walks, approximately 50% of calories burned may come from fat; if she runs, approximately 35% of calories burned may come from fat. With these percentages, it appears to make more sense for her to walk rather than run, especially if fat loss is her goal.

However, a 30-minute power walk burns only about 200 calories, which means she will burn approximately 100 fat calories and 100 carbohydrate calories. A 30-minute run will burn approximately 330 calories, which means she will burn 115 fat calories and almost 215 carbohydrate calories.

Therefore, if she is running, she is burning more total fat calories and more total carbohydrate calories than if she power walked the same amount of time. Because you need to burn off 3,500 calories to lose one pound of fat, the running speed looks like a much better approach.

But there is another factor to consider. What if she did not like to run, but preferred power walking instead? She might burn more fat and calories from running, but hate the workout. That might cause her to work out less often, making her weight-loss goal more difficult to achieve. Similarly, she might enjoy running, but find herself unable to last more than 15 minutes. In that case, her workout would be so much shorter, her overall fat- and calorie-burn might be much lower than if she simply walked the full 30 minutes.

The perfect “fat-burning” intensity is different for each person because the intensity affects how long you work out and how much you enjoy it. And those factors are often more important than how hard you push yourself.

The best thing to do is mix up your workout intensities and times. On days when you are short on time, push yourself a little harder. On days when you have some time to spare, go a little easier and work out a little longer.

Consistency and avoiding “workout burnout” are bigger factors in reaching weight loss goals than choosing the perfect “fat-burning” program on a machine that does not know what you enjoy, how you feel on any given day and how many days you are willing to workout.

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Jay Blahnik, a Laguna Beach-based personal trainer and IDEA Health & Fitness Assn. spokesman, has appeared in more than 25 videos and is the author of “Full-Body Flexibility.” He can be reached at jay@jayblahnik.com or health@latimes.com.