Anyone who has been passed in a race by a runner thirty pounds heavier than they are (and it has happened to almost all of us at least once) knows that a few extra pounds do not by any means relegate you to the back of the pack. It may be true that the very best runners have wire-thin frames, but for most recreational runners, slashing your weight to improve your running performance should not be an overriding concern.
Not that you should put aside your weight-loss goals. Many come to the sport, and rightly so, as a way to lose weight and regain fitness. As one of the most vigorous exercises out there, running is among the best regimens for dropping pounds.
All good things, however, come in moderation. Runners are a disciplined lot, often completely devoted to our sport and to getting in our beloved miles every week. For some of us, however, this dogged determination can have a negative underside when it is applied too obsessively to diet and body image. While you should certainly follow a healthy, low-fat diet, understand too that as a runner you are an athlete and you burn enough calories to give yourself some leeway. Feel free to reward yourself from time to time with a few extra calories. It is a frequently heard and well-deserved adage among runners: "I run so that I can eat what I want."
It is in the end a question of balance. Given a healthy diet and a steady exercise routine, your body will find your natural healthy weight on its own. With a little planning, you can help it happen that much faster. But give yourself time. Crash diets are a fantastically bad idea. The best way to lose weight is by dedicating yourself over a long period of time to good eating and exercise habits.
Running for Weight Loss
As weight-loss exercises go, running is right at the top. Although you may hear that lower-intensity exercises such as walking and jogging are better for fat-burning, it's not entirely the case. It is true that the proportion of fat to carbohydrates burned is higher with low-intensity exercise -- the same is true for sitting in front of your computer right now. But high-intensity exercise, like running, burns more total calories per minute (and marginally more per mile), including a higher absolute number of fat calories.
That said, this does not mean that you should necessarily do heavy, intense sprinting to burn the most fat. It's the law of diminishing returns. As you increase the intensity of your workout to maximum effort, your body uses fewer and fewer calories of fat and more from carbohydrate-supplied glycogen. This is because it's easier for your body to convert glycogen into energy—when your body works at peak effort it seeks energy from the most efficient source. So the key is finding the right balance: an exercise level that is sufficiently intense to burn more calories, but not so intense that you stop burning fat altogether.
Turns out that you can find this balance in an easy-paced run of at least forty minutes. Keep the pace below your 10K pace, something more like a marathon pace. To burn this fat most efficiently, it is ideal to run for at least forty minutes per session. While you burn mainly carbohydrates in the first minutes of your run, your body switches to fat as its primary fuel after about 30 minutes.
The key is managing the intensity of your workout. When your running becomes very labored, you're not burning much fat. If you can keep up an easy comfortable pace for 40 minutes, that's ideal. If 40 minutes is a stretch for you, or if you start becoming very tired, take frequent breaks of brisk walking. You will burn more fat with three of these 40-minute workouts per week than you will with six 20-minute workouts.
Over time, too, as your body becomes more and more accustomed to exercise, your muscles become trained to use more fat as fuel, rather than carbohydrates. Because muscle feeds on fat, it becomes a snowball effect: the higher your percentage of muscle, the more fat you burn all day long. Keep in mind that as you lose fat, you may not necessarily lose weight. Muscle weighs more than fat, and you should not be alarmed if you actually gain weight with your exercise program. Look again: you may be gaining weight but losing inches.