Last Updated: February 7th, 2021

Feeling like a balloon again?

Do you feel like you are gaining weight even after running every day?

Don’t know why?

Here are some legitimate reasons for bloating and weight gain after running…

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Bloating and weight gain after running 2-min

9 Reasons for bloating and weight gain after running

1. You have a sluggish metabolism

This is one thing that my sister deals with on an everyday basis.

She has been a regular gym-goer for almost 3 years now.

Also, along with 3 days of gym she runs 2 days a week.

However, her overall bodyweight remained stagnant.


She has way slow metabolism than an average person.

This keeps her bloated even after her workouts and she simply cannot lose weight.

Check with your physician if you have a similar condition.

[Update: She has started using this program for 2 weeks and is seeing some positive changes. However, it is not as radical as the program claims but nonetheless, it seems to be working.]

2. You have hypothyroidism and/or PCOS

Everybody seems to be losing weight running.

However, you on the other hand is running but gaining belly fat.

One major factor that comes into play here can be hypothyroidism.

This will cause your metabolism to slow down and will result in bloating and weight gain.

Another factor can be PCOS or Polycystic ovary syndrome.

This is a huge factor that contributed to my weight gain.

If you are running regularly now, then you will be seeing positive results in some time.

However, I also did some dietary changes I learned from this book. This book is written by a dietician who has great breakthroughs even in morbidly obese cases.

My gyno couldn’t help here as according to her food has nothing to do with PCOS. So, it may or may not work for you. But no harm in trying.

3. Eating Air

Or more like gulping down air.

When you run, you need a lot of oxygen supply.

You tend to breathe through your nose and mouth.

Related: 8 Essential Breathing Tips for New Runners

However, a portion of the air that you are inhaling through the mouth is not going to your lungs.

Instead, it passes through your esophagus to your colon – your poop reservoir.

Now your colon is a funny thing.

It is like a balloon.

It can be completely deflated and be nothing.

However, when that air reaches your colon it inflates up like a balloon causing you to feel bloated.

Although it eventually comes out as flatulence, however, when you are running – its a whole different story.

Running puts a lot of stress on your body and it goes into a ‘flight or fight’ mode.

At that time, the GI tract tends to slow down and will effectively move the air.

Hence bloating…

However, no need to worry…This too shall pass 😉

4. Water retention


When you are running, your body secretes more cortisol  – a stressor hormone.


Your body needs a lot of fuel.

And this cortisol helps your body to produce more ready-to-use glucose a.k.a fuel.

However, when the cortisol level is elevated, your blood pressure also gets elevated.

In such a situation your body starts to retain fluid.

This additional water weight may make you feel heavy or bloated.

Related: 101 best beginner running tips you should have known


Another hormone that is guilty of this water retention is Vasopressin.

When you are dehydrated, this hormone is released.

With an increased level of Vasopressin, otherwise called AVP or ADH, your kidneys will clear less water.

For example: If your body has an overload of water and ADH is 0, then your kidneys will clear around 1000 ml of water per hour.

However, if AVP is raised to 1 pg/ml then this fluid clearance reduces to 250 ml/hr.

So, if you are not having water properly during your runs, you end up retaining more water due to dehydration.

What can be other reasons for this water retention?

Your own body’s wear and tear.

Running is a very intensive sport, it is more so if you are a long-distance runner.

When you do such an intensive workout, your body tissues develop small wear and tear and then want to repair these tissues.

So, it will keep them bathed in body fluid for faster recovery. Effectively, you will retain more water.

This can make you feel bloated and heavy.

However, this excess water will drain out of your system in a couple of days.

You really cannot do anything here.

If you feel bloated after marathon, do yourself a favor – don’t stand on that weighing scale.

You will save yourself for a lot of heart ache.

What causes bloating after running? If you are dealing with bloating after running here are the causes that is keeping you feeling full even after running.

What causes bloating after running? If you are dealing with bloating after running here are the causes that is keeping you feeling full even after running.

5. Eating a heavy meal before running

Before running, you must absolutely eat something.

All of you know that.

But how much?

Sometimes, we go a little overboard and stuff ourselves with a lot of food.




When you run, blood flows away from your stomach.

It gets redirected to more active parts of your body.

This makes your stomach less efficient with food digestion.

If you eat a lot of food before you run, your food will sit in your stomach undigested.


You guessed it right – bloating.

6. Indulging in bloating triggers

Eating a heavy meal before run is one of the biggest bloating triggers.

However, there are some others like:

  • Fatty food
  • Sugary drinks
  • High fiber food

All of these can cause bloating and gas when consumed before the run.

What should you do instead?

Train your stomach…

It is easier said than done…

However, if you have something that is easily digestible then you can reduce this problem a lot.

For example, you can have one apple or a banana before your daily run.

You also need to eat it at least 20 min before you go for a run.

Else, they may also cause you some sort of GI distress.

Another thing you need to focus on is your calorie intake and hydration during running (especially for longer runs) if you want to escape bloating.

7. You did not do a test-drive

Not taking your running gels or dinks – a.k.a running fuel on a test drive may be one of the biggest mistakes.


Every runner’s body is different…

How your body will react to a particular sports drink or gel, you may never know.

As we already know that we should not try anything new on the race day – it is applicable for your running fuel as well.

So what should you do?

Try out different running gels and sports drinks (never together) and see what suits you.

Take them with sufficient water and in the required quantity – you will be just fine.

Here is a comprehensive guide of the amount of water you need for each brand of running gel.

If you don’t select a gel that works for your body, you will have to deal with the subsequent bloating and weight gain after running.

8. You are eating more than calories than you can burn

This happened to me when I started running.

I thought I can eat whatever I want as I’m working out.

Actually I never thought about the number of calories needed by a runner.


I was running but not losing belly fat – or so to speak, fat.

Apart from my PCOS, another culprit was my overeating.

It took me some time to realize and some lifestyle changes to deal with both of them.

You may be doing the same mistake…

Can’t be sure?

Well, then just observe yourself for a couple of days.

You will have a clear picture.

Now how will you make a practical observation of your eating?

Maintain a food log – duh!

Note down everything you eat in a day for 3 to 4 consecutive days.

Your eating habits and patterns will emerge.

Are you gaining weight from running? Here are the reasons for weight gain while running.

Are you gaining weight from running? Here are the reasons for weight gain while running.

9. You are skimping on sleep

I know, it may sound rhetoric, but hear me out.

Less sleeping causing you to gain weight over time.

Related: Running For Weight Loss: The Ultimate Guide

Also, less sleep causes another problem which is less evident.

If you don’t sleep properly, your peristaltic movement is affected.


In simple terms, your bowel movement.

Less sleep may lead to constipation and gas.

Your colon will remain bloated and you will have that overweight, filled with gas feeling.

So, if you regularly feel bloated, observe your sleep pattern and if required fix it.


If you have bloating and weight gain after running, then any or more than one of the above reasons may be the culprit.

Don’t worry much, just take the precautions and steps mentioned above – You will be just fine.

Madhusree Basu

Madhusree Basu

Author, Admin

Blogger and a fitness enthusiast. She loves running and Yoga and everything in between. She started running to manage her weight and to eat to her heart’s content. A true foodie at heart she shares whatever knowledge she has gained throughout the years about weight management and fitness.