Gaining Weight From Running? Here are 4 Reasons Why You Could Be Running But Not Losing Weight

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Gaining weight from running is probably not what you expected (or hoped for) when you got into the sport.

If you’re like most runners, you’ve grown to love running and are looking for a way to lose weight and enjoy something you love doing. 

Many people start running as a way to lose weight. It’s true that you can burn a lot of calories and burn fat (depending on your running technique). While both of these often lead to weight loss, the outcome is not a guarantee

In fact, there are a number of reasons why you may be running but not losing weight.

In this article, we’ll explore . ..

  • The various factors that could be causing weight gain when you start running
  • What to do about it, and why persisting with your running is usually the best course.


Let’s jump in!

a person running up stairs

4 Reasons Why You’re Running But Not Losing Weight

1. You Might Be Overcompensating by Eating Too Much

You’ve probably heard the phrase, “abs are made in the kitchen,” which means that exercise and diet go hand in hand when it comes to slimming down or toning up.  

This does NOT mean you have to adopt one of the latest fad diets floating around. What it does mean, is that losing weight comes from a calorie deficit. 

If you’re gaining weight from running, maybe it’s because you’ve started taking in additional calories to fuel your run – but are overdoing it.

If you want to lose weight, you will have to burn more calories than you consume.

Running is usually a great way to make that happen because you can burn so many calories through sprinting or long-distance running. 

But on the other hand…all that exercise makes you hungry!

Since you’re burning so many calories, you’re then having to compensate for the difference by eating more than your normal amount, which could be causing you to gain weight.

Experiment with different sources of fuel and nutrition regimes: I typically recommend consuming a carbohydrate-based snack an hour or two before your run.

Also, stick to natural food and fuel sources – energy bars might seem like a quick solution, but they’re often loaded with calories, sugar, and processed ingredients that your body struggles with.

2. You’re Gaining Muscle

A lady running on a trail with mountains and clouds in the background

When you ask, Can you gain weight from running? the answer is yes. But that’s not always a bad thing.

If you’re doing a lot of HIIT-style run workouts like hill running, or additional strength strengthening, you will be building muscle alongside the cardio you get from running.

Since muscle is heavier than fat, your weight gain could be from an increase in muscle mass. 

The best way to know the difference is the way your body looks and feels – if it’s firmer than usual, that would be from gaining muscle. If your pants are getting tighter or refusing to button, that is most likely from overeating. 

That’s why your metric for your ideal body should never be based on the number on your scale. Ultimately, the best test to tell if running is ‘working’ is how you feel. 

If you’re getting healthy results, you will feel more energetic and strong, and will most likely have a more positive mood. 

If you’re gaining fat instead of muscle, you’re more likely to feel sluggish, groggy, and have symptoms of depression. 

When it comes to gaining weight from running due to building muscle, that’s a good thing! Keep doing what you’re doing – your body is getting healthier and stronger.

Man running in an urban environment wearing a tracksuit and headphones

3. You Might Be Experiencing Swelling After A Hard Workout

When you start any exercise program (but especially if you’re training for a long-distance race!), it’s perfectly normal for your body to go through some changes.

When exercise puts stress on your muscle fibers, that causes micro-tears, which can then cause inflammation.

The body immediately works on healing those microtears (part of the muscle-strengthening process). To do that, it sends excess water to the area to help the healing process, which can then show up as water weight gain after running. This is one situation where running does make you gain weight, but not in an unhealthy way.

If you’ve just started running and gained weight, or if you find yourself gaining weight from running everyday or suddenly increasing your running intensity, then water weight gain may be the cause of your weight gain as your muscles adjust to an increase in intensity.

If you’re a bit shocked when you look at the scale, keep in mind that it could just be a natural part of the body’s recovery.

In this case, all you need to do is make sure you’re eating properly, giving your body adequate time to recover in between runs, and go ahead and stick with your plan.

Man in nature in running gear with hands on knees

4. PCOS Could Be Causing Your Weight Gain – Not Running

Polycystic Ovarian Syndrome is a condition that affects 6% to 12% of women. Most women are diagnosed when they try to get pregnant and have difficulties doing so, since the hormone imbalances in PCOS usually cause unpredictable menstrual cycles. 

But another side effect of PCOS is insulin resistance, which means the body can produce insulin but can’t use it properly.

Many women with PCOS become overweight because of insulin resistance. 

It’s normal to turn to running as an obvious solution to losing that excess weight, then find yourself frustrated because you’re still gaining weight, even though you’re sticking to the training plan and healthy diet.

If you do have PCOS, you may be thinking that running is causing the weight gain; in fact, it’s likely just a symptom of the disease.

Dr. Kimberly Gecsi, OBGYN at UH MacDonald Women’s Hospital in Cleveland, Ohio, told Outside Magazine that running and exercise are still a great way to treat symptoms of PCOS (including weight gain).

You just have to follow a different diet than other runners.

Instead of fueling your running with carbohydrates, focus on proteins and fats (like nuts, avocados, and fish) instead. That, combined with possible hormonal supplements like contraceptives, can help you lose that extra weight.

But just because you find yourself overeating to compensate for the calorie deficit, does not mean you need to give up on running. 

a lady in running gear with her hands on her hips in a canyon

Related: Ideal Body Weight Range Calculator

Healthy Ways to Drop Pounds from Running

We’ve mentioned that the calorie deficit is an important aspect of losing weight. But here’s what that does NOT mean: It doesn’t mean you need to eat less than you feel you need or deny your body the chance to eat when you feel hungry. 

The effects of starving yourself for a calorie deficit are serious but are especially dangerous for runners. 

If you don’t get the nutrition you need to fuel your run, you can end up getting dizzy or even passing out during your run. 

Your muscles will not develop properly, since they need healthy levels of carbohydrates and fats to use for energy. When you push yourself past those healthy limits, you end up with lifelong injuries. 

Here are two ways you can still get a calorie deficit – and lose weight – from running. 

1. Build those muscles

a lady punching the air next to a lake

Many runners will jump right into a training plan and run medium to long distances 5-6 times a week. But this is not necessary for accomplishing your distance or speed goals; it’s also not necessary for weight loss. 

The best way to run farther, faster, and lose weight, is by incorporating strength training into your running routine. When you build muscle, you burn fat, which in turn tones your body and makes you look more ‘fit.’ 

As I mentioned above, building muscle could make you gain weight, but focusing on the number on the scale should never be the most important metric.  

Whether you want to lose weight to get healthier or to look a certain way, you’ll accomplish both by building some muscle too. 

See our weightlifting guide for runners – it’s our recommended approach for strength training effectively.

a man wearing sunglasses in the race starting position on a road in nature

2. Eat as much as you need…but eat better. 

Keep in mind that the reason you’re hungrier as a runner, is because your body is asking you for more fuel. When you think of food as fuel for running, you’ll probably make some different menu choices. 

What do we mean by fuel? It’s the different resources the body uses to create the level of energy you need for running. 

Related: Walking for Weight Loss

3 Healthy Foods to Help Runners Control Their Weight

You already know that you should eat more vegetables, cut back on sugar and processed foods, and eat lean meats over reds if you want to lose weight. 

But the important thing to remember about eating for fuel/weight loss is the quality of your calories over the number. 

a plate of sweet potato fries and greens

Eating 1400 calories that are packed with nutrients your body can absorb for your next run is much more effective for weight loss than consuming the same amount of calories full of empty carbohydrates that won’t be there when your body needs them. 

  1. Brown rice: swapping out white rice for brown is just a small tweak in your diet, but will give your body more complex carbohydrates from the get-go. (If you’re on the fence about the importance of complex carbohydrates, read this article.)
  1. Salmon: This is not only one of the best sources of protein for runners, it’s also full of Omega 3-fatty acids, which improve your heart, lungs, bones…and speed up your metabolism. 
  1. Sweet potatoes: Swapping a white potato with a sweet potato will put way more nutrients inside your body that it can store for later. Sweet potatoes are full of Vitamin A, Vitamin C, Beta-carotene, and Menganese. These all support your immune system, vision, prevent respiratory infections, and support healthy blood sugar levels. 
a woman running on a trail next to the sea

You can read more on the best fuel for runners here, but there’s one thing you need to remember when it comes to gaining weight from running vs. controlling or losing weight when running; 

If you approach the process from a “quitting” perspective (example: I need to quit eating sugar, or quit eating steak…etc.), you’re bound to slip up..and then give up. 

But when you approach the process from a perspective of replacing one thing for something better, you’ll see far better results. Instead of, I need to quit eating french fries, try, I’ll eat baked sweet potato fries and season them with something delicious. 

This puts your state of mind in a more positive frame, so that even when you do slip up (you’re only human, after all), you’ll be much more likely to get back up and continue the next day.

That’s what will ultimately help you stop gaining weight from running – and help you enjoy healthy food rather than dreading it!

A lady running on concrete, overlaid with text saying 'gaining weight from running? Here's why you aren't losing weight'
Photo of author
Mia Kercher is a hiker, cyclist, and runner. After finishing her first marathon in 2013, she continued the sport but found a new passion in trail running. She now explores the glorious mountains in Portland, Oregon.

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