Will I Run Faster If I Weigh Less?

Last week, I wrote about Running Faster to Get Faster, which basically states that if you want to improve your race times, you are going to have to do some speed training, and I listed my three favorite speed workouts.

I was intrigued by one of the comments on that post. I was asked if losing weight was important in order to run faster. That is quite a complex question, and while I answered to the best of my ability at the time, I wanted to do a little research and address the question fully.  Here is the question:

I’m curious, do you know how weight affects a runner’s speed? I’ve noticed when I’m at a race awards party, the winners are nearly always very petite and lean. If I want to be faster, should I also be working on being leaner in addition to speed workouts?

I think that is a great question. Because it’s true, isn’t it? When you look at the runners who win, both men and women, they are frequently very lean, and sometimes quite petite. Here is my original response:

Weight Loss - running

As you can see, my answer was a little on the lines of  “yes, but no, but yes, and be careful.

It is a complex question, if only because runners can be intense types who can fall into the trap of thinking if a little weight loss is good, more would be better.

Improving your V02 Max is one way of getting faster. V02 Max is the maximum amount of oxygen a given runner can use per unit time per unit body mass. That means the lighter a runner is at a certain fitness level, the faster they will run (at least in theory). Remember, though, that not all excess weight is body fat. Muscle weight is entirely different, and can contribute to performance despite its high density.

Estimates concerning an ideal weight for performance can vary. While some running coaches would say that the ideal weight for a distance runner would be about 10-15% below the median weight, frequently world class distance runners can be up to 10% below that. But while these world class runners perform much better at weights significantly below average, there must be limits in terms of what is beneficial or even healthy.

So how much does weight loss affect speed? Joe Henderson, author of many books on running and training, estimates that a runner with a 10 pound weight loss can run 20 seconds per mile faster. That being said, you still have to look at the big picture. If a man who is six feet tall and weighs 200 pounds loses 10 pounds of fat, he will increase his speed by that 20 seconds per mile (on average). What if that man already weight 170? Would a 10 pound weight loss lead to the same speed gain? Or would the possible loss of muscle actually slow him down?

Using myself as an example, I probably weighed around 145 when I was training seriously, maybe a pound or two less. I am 5’8”, and that is a good weight for me. I know that when I get below 140 I certainly look like a distance runner, because my cheeks tend to cave in. Would I have run faster though? I don’t know.

One of the problems with the thought that weight loss leads to speed gains is, as I alluded to above, that many runners take it too far. They always feel that if they just lose another five or 10 pounds, they will get the edge they need. This can lead not only to eating disorders, but to increased injuries and illnesses, decreased performance, and for women, the Female Athlete Triad, the combination of disordered eating, bone loss, and cessation of the menstrual cycle.

So while the typical American may be out of shape and overweight and could benefit from a weight loss program, competitive runners are typically much closer to an ideal weight, both for health and performance purposes. Remember that more is not always better.

In conclusion, I would say that if you are overweight, even moderately, some weight loss will help you become faster. If you are already at a healthy weight for your height, be very careful about further weight loss, because while it may lead to slightly better race times, there may be other consequences to your health and to your future performance.

Remember, I am a personal trainer and a coach, not a doctor or psychologist. I wrote my own opinions, researched and read other opinions to write this post.  You should always do what is right for you and your body, and if you are in doubt about what that is, you should speak with your own doctor.

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  1. says

    Great post! So glad you addressed this issue. I have been in ED recovery for a few years now so I know how just the idea of losing weight to help get better at something can be tempting to some people. People with eating disorders are usually perfectionists.So I could see some people taking it the wrong way. Sorry I am rambling lol! Love this post!
    Jo recently posted…Food Quote of the WeekMy Profile

    • says

      One of my biggest fears as a coach of young people is that the teenagers that I work with will develop eating disorders in their quest to become better runners. Teenage girls in particular, have so much pressure to be thin, then add in what on the surface looks like a legitimate reason for weight loss, and you have a potential recipe for problems. I was rambling a little too. Thanks! :-)
      Debbie recently posted…Will I Run Faster If I Weigh Less?My Profile

  2. says

    Great post!!! This past weekend I PR’ed my 10k race 25 pounds heavier than I was when I set the last record. I think at that point I was way too thin, bordering on an ED and I had to learn that I am faster and stronger when I am properly fueled. Thought I work harder at this weight and once a find a happy balance somewhere in the middle I will surely improve my times, skinny or thin aren’t always what is best for your body!
    Sarah MomRunningonEmpty recently posted…Am I really #SpartanStrong???My Profile

    • says

      Excellent point. One of the commenters further down the page, Douglas, spoke to adding muscle, which will make you weigh more, but you will be leaner and stronger. That runners should focus on how their clothes fit, not at numbers on a scale.
      Debbie recently posted…Will I Run Faster If I Weigh Less?My Profile

  3. says

    I have often wondered if losing a few pounds would help me go faster — and I think that it would. However, it’s really hard to deviate from my natural, happy weight and I don’t think it’d be worth it. CErtainly an interesting topic of conversation though!
    Ericka @ The Sweet Life recently posted…Crossfit: From Hating to Loving My ArmsMy Profile

    • says

      It is definitely a complex question which leads to even more questions. It depends on current weight, goals, muscle vs. fat weight. Plus there are a lot of psychological implications. Some people are more prone to develop eating disorders and could potentially get caught up in the belief that losing even more weight would lead to faster times.
      Debbie recently posted…Will I Run Faster If I Weigh Less?My Profile

  4. says

    I think you addressed this perfectly. VO2 max goes up with weight loss, but there is a limit. Go too far, and not only are you in danger of the female athlete triad, but you won’t have the energy required for the workouts, either. It’s never easy, is it?
    misszippy recently posted…How do runners say good-bye?My Profile

    • says

      Yes, agreed! and it really comes down to a science, ya know?! too far is dangerous. Wells aid friends!

  5. says

    You make some great points. Sometimes we can get to focused on numbers to the detriment of our health. But reaching a healthy weight can improve speed and improve how running feels. I know my runs feel dramatically different from when I started trying to run and was about 10 lbs heavier.
    Pamela Hernandez recently posted…The Best Fit Things to Do in SeattleMy Profile

    • says

      Absolutely true. What always scares me as a fitness professional is knowing that runners tend to think if a little is good, then more must be better. I have to watch my cross country runners so carefully, especially the girls. The new runners frequently have some weight to lose, and when they do you really have to educate them. And it’s not like teenage girls don’t get enough pressure about their weight and looks already!
      Debbie recently posted…Will I Run Faster If I Weigh Less?My Profile

  6. says

    one big thing you forgot to mention, muscle weighs more then fat, but takes up less space. as you train you build muscle and burn fat. it often can happen that you actually gain weight, especially if you are getting significantly stronger or faster, but you can actually be thinner and have lower body fat. as an athletic trainer i tell my athletes not to focus on what the number on the scale says, but more on how their clothes fit. if really worried about how ‘fat’ they are to get tape measure and measure their waist regularly or get body fat checked with calipers. actual weight, and height/weight charts can be very misleading. in high school and college i had 5% body fat (cross country runner) but according to height/weight charts at doctors office i was borderline obese because i was all muscle. so don’t worry about the scale, a mirror and your clothes tell you more…

    • says

      I think this is so true, especially for my body type — what I’d call “skinny fat.” I’m on the lower end of the healthy weight range, but I have excess belly fat that I’d love to convert into muscle! I think we (as a society) focus too much on calories and pounds instead of more important metrics like nutrition and body fat %.
      Jen recently posted…Weekly training recap: SF2HM Week 7My Profile

      • says

        Remember that gaining muscle can help your performance, strengthen your bones, and improve your metabolism. Also remember that fat can’t be converted to muscle. We can only lose fat, and gain muscle through appropriate strength training. And improving strength in your core will definitely improve your running.
        Debbie recently posted…Will I Run Faster If I Weigh Less?My Profile

    • says

      Great points. Yes, it is so true that muscle gain (along with fat loss) can lead to actual weight gain, something that will send most runners into a panic if they are not aware of what is happening. The idea of clothing fit, or actual measurements is a great one. And if the runner is training in such a way to improve speed they should see improvement in their running time.

      I still think there is a small little bug that sits on our shoulder that whispers less weight = more speed. Your runners are fortunate that they have you to remind them of the truth about body mass. Not everybody has a coach or trainer, though, so I hope to educate a few people. I thank you for adding to the conversation.

      I am old enough to remember when coaches were the ones to insist that their runners lose more and more weight. In fact, I’m sure it still happens in many instances.
      Debbie recently posted…Will I Run Faster If I Weigh Less?My Profile

  7. Chris says

    Thank you for a great answer to a question which is more complex than it seems. So many variables goes into this equation. I guess it’s best for me that if you are overweight, loosing weight will improve your speed. If your weight is ideal for your body type., losing weight might be a disadvantage for you.
    Chris recently posted…Burn the Fat, Feed the Muscle ReviewMy Profile

    • says

      That is true. Taking all the psychological issues out of it, yes, if you’re overweight, you can probably get after if you get down to your healthy weight. If you are an ideal weight, probably not.
      Debbie recently posted…Will I Run Faster If I Weigh Less?My Profile

  8. says

    Great post. I did lose about 10 lbs before my last marathon (not by choice but lost it all the same) and carved 11 minutes off my time. I’m 5’8 and was about 146 before the weight loss. I found that the perceived effort was the same but I guess, the lower weight, translanted to a faster time.
    Robin recently posted…Next Up: Sulphur Springs Trail Run (Pacing Duties)My Profile

    • says

      That’s true. It takes less energy to move less mass. There is no doubt that losing weight to achieve a healthy, lean weight will help you run faster. What makes it so complex is the idea that, hmm, will another 10 pounds make me even faster? It is easy to get caught up in that concept, even for healthy people with no history of disordered eating. That’s when it can lead to problems.
      Debbie recently posted…Will I Run Faster If I Weigh Less?My Profile

  9. Katelyn says

    Great, balanced post. Thank you for your thoughtful blog.

    • says

      Thanks, Tamara. This is the question that always kind of scares me to answer. There is a lot of disordered eating in high-level running, simply because of the idea that you will run better if you weigh less. And a lot of people who already tend toward disordered eating use running as their fitness of choice…it’s such a good calorie burner. So I am always hesitant when I answer the question. Hopefully, this explains it pretty well.
      Debbie recently posted…Will I Run Faster If I Weigh Less?My Profile

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