Before I answer the entitled weighty question, I want to clearly support the idea that almost anyone can run and we don’t have to be preoccupied with weight or weight control to participate successfully in our sport. Age group runners come in every size and shape. One of the great things about cross-country and track in middle or high schools is that it is a no-cut sport. Everyone can participate. We even have the Clydesdale category in triathlons to recognize the bigger runners.
Ok, now to the question of whether weighing less can improve your running. The answer is a qualified yes.
VO2max (the maximum amount of oxygen you can process) is measured with body weight as part of the calculation. The more you weigh, the lower your VO2max and the lighter you are the higher your VO2max given the same conditioning. A higher VO2max is a good thing. Though it is not the best indicator of performance (it lags behind lactate threshold and vVO2max) a larger VO2max means you do have a larger “tank” to call upon. It is very likely in fact that a more efficient and powerful runner will out perform the runner with the higher VO2max.
So, though the lighter runner will have an advantage over the heavier similarly trained runner there is more to consider. How many of your competitors are trained just like you or you like them? Odds are there are wide variations in preparation. I introduce this consideration because you should address your overall training first in getting faster.
For the very reasons stated above, you want to become more efficient and powerful. You want a faster vVO2max (the minimal pace at which you reach your VO2max). All other paces are a percentage of this pace and so as you speed this up you drag all the other times with it. You also want to be able to process lactate superiorly. These things are accomplished by a comprehensive approach to your training which includes phases which move through getting you stronger (running specific strength), getting your basic speed faster and through race specific preparation. (By the way, notice that none of those phases include miles and miles of mindless “base” training.)
Here are my recommendations regarding weight loss and improving your running performance.
- If your body weight is already within normal ranges your goal should not be related to body weight. Start training appropriately instead.
- If your body weight is below normal ranges you should never consider weight reduction in your considerations for improvement. The adverse health considerations far out-weigh any effect on running (which will most likely be at best minimal and far more likely detrimental).
- If you are truly over-weight you may benefit from weight reduction. Your BMI (body Mass Index) or fat percentage are important numbers to take into consideration not just the number on the weight scale.
As part of a holistic and comprehensive approach to your running you should get a full evaluation of your diet. Do not under any circumstances get into any of the popular or fad diets and absolutely do not get into a low-carb diet. If you do not have an athletic diet, you will not have the energy available to do your workouts as prescribed. To workout, calories are required and carbohydrates are your staple. Therefore you will not be completing workouts at the right paces or completing the distances. If your workouts suffer, you don’t burn the number of calories you should and in the end will lose less weight instead of more.
There are two other points to make. High intensity workouts will have more effect on your metabolic rate (i.e. burn more calories even at rest). Increasing lean muscle burns more calories.
FYI – Each mile you run will burn approximately 100 calories. There are approximately 3500 calories in a pound. This is variable of course depending on the size of the individual, pace, terrain, conditioning/efficiency, etc. But, this figure is an easy and valid ball park figure. Remember, you have to have a calorie deficit at the end of the day to lose weight.
In all my years of coaching I rarely advise a runner to lose weight to get faster. Don’t try to be someone else’s “ideal” weight. If you train better; eat appropriately apportioned, spaced, smaller meals; cut out junk food, alcohol, evening snacks and large late evening meals; your weight will most likely “normalize” for you.