I fell into the world of endurance running entirely by accident. In high school, I was the musical theater nerd who got picked last in gym class, and in college, the only sport I participated in was beer pong. After six years of increasingly problematic drinking, I got sober in 2010, which was hands down the best decision I ever made. As time passed, my life got better and better. Unfortunately, my body didn’t follow suit.

All that time I spent drinking had not done my body much good; a year into my sobriety, I was still carrying around the extra 30 pounds of weight I had put on as a result of my habit. And so I decided it was time to do something about it. Something drastic.

I was going to work out.

From the Bottle to Brick Workouts

At that point, I was such a couch potato, I didn’t even own a pair of sneakers. But I was determined to get the weight off, make some positive changes in my life, and become a more active person. I figured since running has the lowest barrier to entry (no expensive gym membership; no feeling like a spectacle on the elliptical machine while other more experienced worker-outers watch and laugh), it was a good place to start. So I bought a pair of cheap running shoes, laced up, and got moving.

On my first run, I lasted less than three minutes before I had to stop on the side of the road, doubled over and gasping for air. It was horrible. But I caught my breath, shook it off, and kept going. The entire run continued like that, with me stopping every minute or so to catch my breath. But eventually, I ran a whole mile.

I was ecstatic. I had never run anything close to a mile, and that "I did it!" feeling of accomplishment was amazing. I wanted more of that. So I decided to keep at it.

EDITOR'S PICK
{{displayTitle}}

I started running with a group of friends, and we pushed each other to up our mileage. One mile turned into two, which turned into five, and eight, and 10. We started signing up for races, first 5K fun runs, then 10Ks. After a few months, we decided we were ready to tackle a half-marathon.

If I could bottle up the feeling I experienced crossing the finish line of my first 13.1, I would—and I’d buy it in bulk. In that moment, high on post-run endorphins, I knew.

I wanted to be an endurance runner.

And so that’s what I became. To date I’ve completed over 15 half-marathons, one full marathon, two Tough Mudders, a Spartan Super, and a Ragnar Relay (a two-day, 200-mile relay race). From 2011 to 2014, racing was my everything.

But then life happened. I got a stress fracture during a race that sidelined me for a few months. One of my running partners got pregnant with her first child and moved across the country. The rest of us moved forward in our careers and our relationships, and we found we had less time for long Saturday runs and race-centric weekend getaways. By the time 2017 rolled around, my racing schedule had dwindled down to a race or two per year. Then a move to Oregon pretty much obliterated my training.

I’ve been in Oregon a few months, and now that things have settled down, I’ve been debating whether I want to get back into the endurance running game. There are so many things I miss about racing: I miss the starting line excitement the morning of a big race; I miss the travel and getting to see a new city through the lens of a long run; I miss the post-race brunches, complete with waffles, home fries, and allthebacon.

Deanna running in a race

But I’d be lying if I said there weren’t downsides. Because my foray into endurance racing was completely accidental—and I had zero athletic history prior to that first run—there were plenty of unexpected (and not-so-pleasant) surprises along the way.

If you’re considering hopping on board the endurance running bandwagon, let me offer a word of caution before you lace up your trainers and sign up for your first marathon.

1. You might not lose weight.

This isn’t everyone’s goal, so if this note doesn’t apply to you, feel free to skip ahead. But as previously mentioned, I personally started running to lose weight. And I did lose weight... until I started training for my full marathon.

Marathon training is a beast; I was running 10 to 15 miles during the week, followed by a long weekend run that lasted anywhere from 12 to 20 miles. So you can imagine my surprise when I got on the scale a week before race day and realized I had gained 5 pounds.

Gaining weight during endurance training isn’t all that uncommon, and here’s why: Running burns, on average, about 100 calories per mile. So if you run 10 miles, you’re burning somewhere around 1,000 calories.

But you know what else happens when you run 10 miles? You’re STARVING. Most runners overestimate how many calories they burn during a long run and end up overeating in response to their insatiable post-run hunger. And when they eat more than they burned, they gain weight.

That’s 100 percent what happened to me. I figured since I was running all the time, I could eat whatever I wanted (including stupid amounts of pizza). But that overindulgence on a regular basis is what caused the scale to creep up.

I had never run anything close to a mile, and that "I did it!" feeling of accomplishment was amazing.

If you’re thinking about running a marathon just to lose weight, there are better (and easier ways) to drop a few pounds. But if you do sign up for an endurance event, make sure you keep your caloric intake in check, or you might find yourself adding lbs. instead of shedding them—no matter how many miles you run.

2. It’s rough on your body.

Even I, the inexperienced athlete, knew that running for four to five hours at a time would be rough on my body. But I had no idea exactly how rough.

When you run long distances, there are issues that occur in your body you’ll 100 percent be aware of, such as sore muscles, joint pain, and chafing (which is just as fun as it sounds). But there are also issues you won’t necessarily be aware of—and they can be dangerous.

Long runs can cause dangerously low sodium levels, lowered immune function, inflammation, and even kidney damage or heart problems. Luckily, most of the damage done to the body during a long run is temporary, but it’s definitely something to be aware of. If you understand how endurance running negatively affects the body, you can take the proper measures to protect yourself (like by monitoring your fluid intake during a race to keep your sodium levels from dipping too low).

3. There are no substitutes for proper training.

When I was training for my first half-marathon, I followed my training plan to the letter. I never skipped a workout, and as a result, I felt great during the race—even finishing about five minutes faster than my goal time.

EDITOR'S PICK
{{displayTitle}}

But as I started racing more, I got more relaxed in my training. If I missed a run, I didn’t worry about it. If a last-minute race opportunity came up, I jumped on it—even if I hadn’t done a long run in weeks. I figured once I was in "marathon" shape, I could get a little lax with my training plans; I thought muscle memory was enough to carry me through a race I didn’t train for. But I couldn’t have been more wrong. When it comes to endurance running, there are no substitutes for proper training.

I learned this lesson the hard way in 2013. I decided to do a half-marathon with my friends—even though I hadn’t trained in over a month. I struggled through the entire race, and as I was pushing my way up a steep incline around mile nine, I felt a searing pain in my knee, which turned out to be a stress fracture. It was a month before I could walk without crutches and three months before I could even think about tackling a run again.

If you want to be an endurance runner, you need to commit yourself to the right training… or suffer the consequences.

As I sit here writing this, I’m not sure if a return to endurance running is in the cards for me. I’ve been running three to four miles at a time, and right now, that feels good to me. But what I do know is that if and when I make the jump back into endurance running, it won’t be accidental. This time, I’ll be prepared.

And maybe I’ll cool it (just a little) on all the waffles-home-fries-bacon brunches.

Deanna deBara is a freelance writer and accidental marathon runner living in Portland, OR. Keep up with her running adventures on Instagram @deannadebara.

READ THIS NEXT: 8 Apps Every Runner Should Download Aaptiv phase 2 promo