I am the type of runner that gains weight while marathon training.  Out of the 5 marathons I’ve run in the last two years, I gained weight for 3 of them.  Not a lot, but 4 to 5 pounds.  Once I started really trying to figure out how to get better at the marathon, the issue of weight came up.

I have always been a healthy weight, both before going plant-based and before running, but I was usually at the higher end of normal.  Initially, I started running to lose some weight for vanity, but once I starting running to become a better runner, the way I looked in the mirror became secondary.  I just wanted to become faster.

So for my third marathon, Boston 2015, I lost 12 pounds and PRed by 12 minutes.

I’m not saying that losing a pound and a minute go hand in hand. I put in a lot of training and got much fitter for that PR, but it is clear that carrying less weight makes running easier.  At a certain point, however, if you lose too much weight too fast, you will become weaker, slower, and more injury-prone.  Elite runner Sarah Crouch and running journalist Mario Fraioli warn about the dangers of calorie restriction that they’ve seen first-hand in the running world.  That is not the type weight loss that I am talking about.  To race at your best means to be have the lowest healthy amount of body fat while also being at your strongest and fittest.

I think a lot of typical running articles shy away from a deeper discussion of weight in relation to racing.  Sure, there’s no shortage of weight loss articles for people who need to lose weight for health reasons, but when it comes to marathon training, the big message seems to be fuel.  Going for a run?  Make sure you fuel up!  Just back from a run?  Fuel up with a 4:1 carb to protein ratio within 30 minutes or else!  Running for more than an hour?  Bring snacks!  Fully grown adult runners are essentially being treated like toddlers. And a lot of us are gaining weight.

As a beginning runner, I hungrily and happily listened to that message and packed on the pounds despite how much I ran.  It was not until I tracked what I ate every day on MyFitnessPal, did I realize how much I was over-feeding myself.  And no, I was not the type of person who justified eating an entire pan of brownies because I ran long that day.  I gained weight because I ate too much healthy food.  My mid-day smoothie habit, for example, full of nutrient-rich plant foods like greens, chia seeds, a banana, some oats, walnuts, almond milk and berries weighed in at nearly 700 calories!  Once I could get an accurate picture of my intake, I made changes and adjusted my portion sizes.  I set the app to lose between a half pound to a pound a week and was able to get to my goal weight on race day.  I’m not going to say it was easy, but running isn’t always easy either.

Food is deeply personal and powerful.  Many people’s lives are destroyed because they eat too much and others because they eat too little.  Some runners who meticulously log every mile, workout, and heartbeat, would think it frighteningly neurotic to track their calorie intake. I think that is a mistake. Calorie and nutrient intake is a critical component of racing and training well so it should be obvious that logging what we eat is yet another data point on the path to a PR. I am not suggesting that every runner record every bite that they swallow for the rest of their lives, but it can be very enlightening to track for a few weeks to see if you can pinpoint ways to improve your habits.  I do not track my intake daily anymore, mostly because I’ve learned what foods and portions work for me.  But when I’m getting ready to start a training cycle, food tracking is a great way get back into the habits that keep me lean.

So what is your ideal race weight? Matt Fitzgerald has a calculator but it requires that you know your body fat percentage.  You can estimate it with some cheap calipers, but the accuracy is not great. I chose to get my body composition analyzed in a BodPod at my local university for $35.  The results in 2015 showed that I was moving in the right direction and was not getting too skinny.  I went back a year later two months before Boston 2016 and was happy to see that although I was about the same weight, I had lost 2.4% body fat and gained 2.5 pounds of muscle.  Even though I ended up adding a couple more pounds by race day, I ran the course more than 15 minutes faster in 2016.

My next challenge is to figure out how to maintain closer to race weight when I’m not racing to avoid the 6-10 pound swing I’m experiencing.  Leaning up for this year’s Boston was harder than the first time and I suspect it will get harder each time.  Some of that will be due to simply getting older of course, but I’m also starting to think about the effects of a slowing metabolism from the weight loss itself.  This article about former contestants from The Biggest Loser regaining all their weight and more is a very interesting look at how hard your body fights to regain weight loss.  I suspect that the very unhealthy way these reality-show contestants lost their weight has a compounding effect, but there may be some good lessons to learn for everyone.

Body weight is an important part of being your fittest and your fastest.  Training and experience will trump being light weight every time, of course, and that only comes with time and hard work.  But I don’t see the long wait as a negative.  It means that I have the capability to continue to improve for a long time, even if my weight isn’t at its lowest.

About Claire


Coach Claire has helped hundreds of runners chase their dreams and conquer big goals. Her coaching philosophy combines science-based training, plant-based nutrition, and mindset techniques to unlock every runner's true potential. She's an ASFA certified running coach, sports nutrition specialist, a 2:58 marathoner, mom, and borderline obsessive plant lover.

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