Does Running Cause Weight Gain?
The short answer is, yes, it can.
I'm writing this because I am currently leading a women's 40+ fitness group. Nearly all of the women in the group want to lose some body fat—no surprise there, right? Weight loss is the most common reason people start exercising. As with all of my fitness groups, I have a few participants who are recreational endurance athletes. They train for events like marathons, triathlons, or long-distance bike races.
As I commonly find with 40+ female endurance athletes, these women are struggling to keep the weight off. They're training hours every week and not shedding weight. Some are gaining weight despite the hours of cardio. What gives? How is it possible to do all that cardio and gain weight? HELP!
Before we jump into running and weight gain…
Before I discuss why running can cause weight gain, I want to make two points. First, mammalian metabolism is one of the most complex things in the universe. We are far from completely understanding it. This is why two people can eat and exercise the same way and have completely different results. Second, I will always encourage people to do activities that they love. I will also be honest with them if they have competing goals.
Chasing the calorie burn
"But I lost so much weight at first! Why is this not working now?" ~Me, three years into triathlon training
If I had to guess, many women who get into endurance sports do so because they want to lose weight. And, at first, they get amazing results. They lose weight, get lean, and are in the best shape of their life. I experienced this when I began training for triathlons in my early 30's. I got lean the first year. 12 months later the results stopped. Two years later, I began slowly gaining weight, despite running even more miles than when I started.
Why did I get such a great result the first year and why did it stall after that? Glad you asked. I lost weight the first year because the endurance work was a novel stimulus. My body was inefficient at the activity, so it had to burn a lot of energy to propel me forward. The first year, I might have been burning 600 calories an hour during a workout (this is a high estimate for calorie burn). A year later, my fitness was at a much higher level, which meant my body was more efficient at the activity. I was running the same distance and/or time, but burning fewer calories. My hourly burn might have dropped from 600 to 400.
This is exactly what endurance training is supposed to do! The goal of endurance is to make your body efficient at the activity you are asking it to do! What most people don't understand is that means you are actively training your body to do more while burning less. Read that again. Yes, you will be super fit. You will be able to run long distances (which is the point of distance training, right?) But this is not a great long-term strategy for fat loss. For fat loss, we do NOT want our bodies to be more efficient with calories!
In this situation, to keep losing weight while running, I would have to run more hours or miles to burn the same amount of calories. Instead of running for just one hour, I might have to run for two. Unfortunately, many women end up overtraining because they are chasing the calorie burn.
Running is not a good weight loss strategy for the average person
Look at the top endurance athletes in the world. You can easily tell their genetics lean toward small, thin, low muscle mass, and high metabolism. Most recreational runners are "average". I don't mean that as an insult. The average runner has a job, kids, life stress, and isn't necessarily genetically gifted as a runner. You can go ahead and train for marathons, but that doesn't mean you will look like or have the metabolism of an elite marathoner.
Some other unfortunate problems come with being an "average" endurance athlete. I call this the endurance triad. These are the three main reasons long-distance runners sometimes end up gaining weight:
1. Long cardio sessions make you hungry. Most endurance athletes have noticed that they are hungry one or two days after a long run or bike ride. It is very easy to eat more than you are burning. Remember, you have trained your body to be more efficient at the activity, so you probably are not burning as many calories as your Garmin says. It's also easy to get into that mental game of "I burned this many calories, so I earned 5 slices of pizza". (Cardio should never be used to "earn" food. You will lose that game. Every time.)
2. Cardio is catabolic. When you train for endurance, you train your body to be efficient at that activity. In an effort to be more efficient, the body will get rid of tissue that requires extra energy. So, it gets rid of muscle. Muscle is metabolically expensive tissue. It burns calories. Your body doesn't need much muscle to run a long distance. In fact, the less muscle you have, the more efficient you will be with calories and running. Unfortunately, up to half the initial weight loss experienced when first beginning endurance training comes from muscle. The less muscle you have, the slower your metabolic rate will be. This leads to a slow weight gain over time.
3. Long cardio sessions increase cortisol. Distance running can significantly increase cortisol levels, the body's stress hormone, especially when performed at high intensity or for extended periods, potentially leading to imbalances if not managed with proper recovery and training practices. This is because the body perceives long-distance running as a stressful activity, triggering the release of cortisol to help mobilize energy during exertion. If cortisol is chronically elevated, it can lead to belly fat deposition and weight loss resistance.
How do I lose weight and keep it off forever?
To lose weight and keep it off long-term, you want to train your body to be less efficient at burning calories. You need to send a strong signal to build metabolism. This means you have a decision to make: is your number one goal endurance and being good at long-distance running? Or is your number one goal fat loss? Your goal should inform your training and fueling practices.
If the goal is fat loss:
Focus on building muscle and getting strong. Get on a structured strength training plan and train 3-4 times per week. Strength training doesn't burn many calories, but if you are looking at exercise as simply calories out, you are missing the point! Strength training builds muscle. More muscle equals higher overall metabolism. You will burn more calories while you sleep, sit at your desk, or sit on the couch. This is working smarter, not harder!
Perform low-intensity cardio for heart health, 2-3 times per week. I am not anti-cardio! But your cardio sessions should not be about burning calories, because your body will simply adapt and burn fewer calories. The goal of cardio should be heart and mental health. Period. It is completely okay to run 3-5 miles a few times per week if you love running. But long-distance running is sending your body a confusing signal when it comes to building metabolism.
Track your diet. Figure out how many calories you are eating to maintain your current weight. That is your baseline calories. From there, you can decide whether it is appropriate to cut or build. It will also help you learn how much protein, carbs, fiber, and sugar you eat.
Prioritize sleep. Sleep is like the reset button for your body. Muscle recovery happens when you sleep. Sleep also plays a crucial role in hormonal balance to support weight loss.
Give it time and get some assistance. If you are transitioning from endurance sports to lifting, I know this is a scary time. You may be afraid that you’ll gain a ton of weight because you are decreasing cardio. It can help to have a coach in your corner. A coach can get you on an appropriate strength plan and support you through this tough mental process.
Thank you for reading! Have a question about fitness or nutrition? Ready to set up a discovery call to discuss your goals and get on a plan? Send an email to kellybailey1980@gmail.com