Working Out & Gaining Weight Instead of Losing

Nothing is more frustrating than stepping on the scale after consistently eating healthy and working out and gaining weight instead of losing.

Worse yet, you’ve crushed your longest run ever, yet the following morning Grrrrrr the scale has risen!!


If you’ve been working out but gaining weight, let’s talk about the culprits and when NOT to worry.

Why You’re Working Out and Gaining Weight Instead of Losing: What’s Normal and What’s Not

First off, don’t panic.

Second, we all KNOW that the scale isn’t the best measure of our bodies or our progress, right???

None the less, I know I’ve found myself wondering what the heck is happening and based on discussions with friends, you probably have too. Is marathon weight gain a must? And is all this running making us fatter?! Uh no.

Muscle Inflammation

A required part of running or strength training is that we stress the body and thereby breakdown muscles. The result of this inflammation is our body retains water to help with the repair process.

So after a lift, a long run or an interval session you might notice the scale is up for a few days.

Once the inflammation recedes, that water will drop and you should have built some muscle which will speed up your metabolism.

Carbohydrates Cause Water Retention

In order to adequately fuel your workouts, you need carbohydrates.

But it’s also true that carbohydrates can cause the body to retain water. This is a good thing for runners who want muscles to be plenty hydrated prior to long runs or summer runs.

Yes, this is also a common reason for weight loss on high fat diets.

WATER. They are losing water weight, not fat. Do not trick yourself in to believing that by reducing carbohydrates you’ll lose weight. We know that especially for women it results in hormonal imbalances that long term lead to weight gain and messes with your metabolism.

What we think about while running...what to eat!

Dehydration Causes Water Retention

Are you noticing a pattern here? The number on the scale is going up because your body is working hard, not because you are truly putting on fat.

This is another one that feels counterintuitive, but if you are not hydrating properly or perhaps did a super long sweaty workout the day before your dehydration will cause the body to hold on to all available water.

Building Muscle and Losing Fat

Because muscle takes up less space than fat, it’s very common to see body builders with enviable six pack abs who weigh more than someone looking to lose weight!

This is why we MUST use tools other than the scale to judge progress.

The goal isn’t weight loss, it’s FAT loss.

Eating as a Reward

I put this one last because I know many of you are eating right.

But it’s super easy to finish that hard workout, feel so proud of yourself and then easily justify the cookie, the extra slice of pizza, the extra drink with “well I worked out”.

Suddenly that becomes our default and we are now taking in more calories that we burned.

We KNOW that our workouts are about so much more than the scale, so don’t let it occupy too much of your brainspace. Keep focused on the way it’s making you feel more confident, stronger and healthier.

Gaining Weight When You First Start Exercising

“I started exercising and I’m gaining weight” – it’s a bizarrely common refrain…let’s talk about why!

If you’re just starting a new exercise program or changing to a more intense training plan, then that could be the culprit for an initial increase on the scale.

The reason your body feels like it was run over by a truck when you start working out again after a lull is due to stress in your muscle fibers.

Exercise causes micro tears and inflammation, two culprits the temporary weight gain.

  • Muscles repair damaged tissues through protein synthesis, which requires water retention.
  • In order to properly heal the tears, the body retains fluid in the area.
  • Voila we’ve explained your temporary weight gain.

As your body adjusts to the new program, this will become less frequent and suddenly one day you’re body will shed the water and you’ll also have found yourself losing fat from the work!

If you’re focused on running for weight loss, then I hope you’ll join our Virtual Run Club. Where we talk about how to do it RIGHT and HEALTHY with 8 running coaches and 2 Registered Dietitians.


How To Prevent Gaining Weight After Working Out

A few other factors could be in play if you’re doing everything right, but still unable to lose weight. Or more notably, you see something odd like that scale going up the day after a long run or marathon. It’s NOT FAT.

Drink More Water.

It may seem strange, but dehydration actually increases water retention.

When you’re not drinking enough water, your body retains more water as a safety mechanism to prevent water levels from becoming too low.

Increase Your Sleep Time.

Catching enough zzz’s is so important for marathon training that I dedicated an entire blog post to the subject.

Sleep is key to recovery from exerted efforts, like long distance running or killer workouts in the gym. When we don’t get enough sleep, the hormones that regulate our hunger cravings get out of whack, causing intense cravings.


Incorporate More Rest Days.

If losing weight is the impetus to begin a new exercise routine, then you may feel like you MUST workout every single day.

This is flawed thinking.

Rest days are crucial for the body to recover from the effort, which is when our muscles are able to grow and our endurance to increase. If our muscles cannot repair themselves, then our body is constantly inflamed and inflammation means the body holds on to extra water.

If you want to maintain a daily habit, that’s a fabulous way to stay on track. Just remember to mix your high intensity days and long runs with days focused on mobility or restorative yoga.

Work on Reducing Stress.

While exercise is a great way to prevent stress, if you work full time, have to make dinner, get the kids off to school, plus squeeze in that run, then it could be contributing to your stress levels.

When we feel stress, our brain releases a host of chemicals, including adrenaline and cortisol. Although adrenaline prepares us for fight or flight and may suppress hunger, once it wears off, cortisol takes over.

Known as the stress hormone, cortisol signals the body to replenish food supplies, which may cause us to eat mindlessly. Checkout this detailed post on understanding cortisol and why your stress is making you gain weight.

Consider Working with a Dietitian

If you still feel like you’re doing everything right, then consider seeing a registered dietitian, personal trainer, or running coach.

They can determine if there are other factors contributing to the weight gain and help put together a plan to help you achieve your goals.

Gaining weight from working out isn’t an immediate sign that you are doing any thing wrong or that there is anything wrong with you!!! The reasons above apply to us all regardless of size or shape, so know that all progress takes time and patience.

We don’t run a marathon on day 1 of training and we don’t lose the weight in 1 week of training.

What is your experience with exercise and weight gain?

What tips do you have to share for keeping off

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Working Out & Gaining Weight Instead of Losing is written by amanda for

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