Does marathon training make you gain weight?

Looking like a stuffed sausage during triathlon training in 2010.

Looking like a stuffed sausage during triathlon training in 2010.

It might seem counterintuitive, but running long distance does not always equal a fit-looking body. I say fit looking, because if you can run 25 – 34km once a week for several weeks, you are a fit person. You just might be carrying around a little extra squishiness than if you were, say, lifting weights and doing half an hour of plyometrics a few times a week instead.

What gives? I burn, like, 1,500 calories on my 30 km training runs. That’s like, a whole day’s worth of food!

And herein lies the problem: Marathon training = eat all the foodz + type I > type II muscle fibres = more squishiness.

Not that there is anything wrong with more squishiness. Your body is doing what it needs to do to prepare for the full 42.2. But most people think training to run a marathon will give them that sinewy body they’ve always dreamed of. Unless you’re genetically prone to sinewy-ness, you’re an elite runner or you go into a calorie deficit during training (which I definitely DO NOT recommend), you’re either going to look the same or lose some muscle mass by the time you cross the finish line of your goal race.

So why does this happen?

The answer is two-fold. As mentioned in the formula above, marathon training make you hungry. Hangry, even. Not only does your body require caloric replenishment after your long runs, but also you feel like you need lots of food. It’s the whole, I-just-ran-for-three-hours-I-can-eat-whatever-I-want thing. Sure, maybe you can eat a bit more on long run days. But you’re not running 30 km every day. And sometimes the whole I-can-eat-anything mentality carries over into the week. I would say this is probably the main reason why marathon runners tend to go up a couple pounds during training.

The other reason has to do with muscle fibre types recruited during training. Running long distance uses primarily slow-twitch fibres (type I). These fibres are great for endurance, but experience very little hypertrophy during training. This means you won’t get those defined abs or arms you may have hoped you’d get during training. Ironman athlete, author and fitness professional Rachel Cosgrove does a great job of explaining why this is, even if you continue to strength train, in this article here.

During training for my first and second marathon, I gained about five pounds each time and lost all definition in my arms and stomach. I definitely had the whole I-need-to-eat-all-the-foodz-all-the-time mentality. The same thing happened during 50k ultra training, even though I continued to strength train twice a week. This last time around when I trained for my BQ attempt in October 2015, I only increased my caloric intake on long run days and stayed at exactly the same weight by being careful to eat at maintenance or slightly over. I lost very little muscle mass thanks to incorporating three days of lifting into my training plan and upping my protein intake slightly. My abs weren’t visible, but that didn’t matter. My goal was to run a BQ, not win a bikini competition.

If you’re thinking about running a marathon, do it because you love to run and it’s something you’ve always wanted to accomplish, not because you want to look a certain way. Despite what some fitness professionals might think these days, I still believe the benefits of long distance running or cycling (increases cardiovascular endurance, strengthens lower extremity bones and joints, gets you outside, makes you happy) far outweigh the drawbacks (not great for type II muscle hypertrophy or body composition, can lead to overtraining and overuse injuries) and is a great way to be a healthy, happy human.

Have you trained for a marathon or triathlon and gained weight? Do you strength train while marathon training? How do you beat the marathon training hangries?