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Gaining Weight When Starting Exercise? It’s Totally Normal

picture of woman exercising

Did you know that many people GAIN weight when they first start exercising, even if they eat at a caloric deficit? It’s due to glycogen. Glycogen is a molecule that provides your muscles with energy. With every gram of glycogen, 3-4 grams of water are also stored alongside. 

When we exercise, especially if we haven’t been active for a while, our muscles get activated. The muscles tell the body it needs to store more glycogen. If you start a strength training program, water is also retained as the muscles are slightly inflamed due to the process of muscle repair and growth. Boom – suddenly our weight goes up. 

Picture of Glycogen. Source: Häggström, Mikael (2014). “Medical gallery of Mikael Häggström 2014

This weight can be upwards of 3-4 pounds, and much of it can stick around for 3-4 weeks while your body gets used to the new workout routine! Here are some references (1, 2, 3).

This is GOOD weight though. It’s not fat. It’s weight that helps our muscles work more efficiently. 

I’ve seen it enough times now in my own body, through my research, and now with people sharing their experiences with me that there is a big misunderstanding when it comes to this weight gain. This misunderstanding causes people to give up on weight loss. After all, people are putting MORE effort into losing weight and yet gaining weight!

A Simplified Explanation of Why It’s Okay

Our bodies consist of a bunch of stuff. “Good” weight is lean body weight, such as muscle and bones. Our body also retains an immense amount of water. Fat is generally the “bad” weight that we are looking to get rid of.

Because there’s not yet a super-accurate way to measure the amount of fat we have on our bodies, we depend on the scale to help us get a measure of if we are progressing with losing fat. Unfortunately, the scale measures the good stuff, the water, and the bad stuff, and doesn’t differentiate between any of them.

If you are on a reasonable weight loss plan that enables you to lose a pound a week, the scale would only go down 0.14 pounds a day if you were on track. This is less weight than a small glass of water. Just comparing your weight from the day before doesn’t really tell you anything about how much fat you’ve lost! This is why Luuze uses trend weight: it’s a way to filter out the lies of the scale. Luuze gives you a more accurate measure of whether or not you are achieving your weight loss goals.

When we start an exercise routine, due to the glycogen and the water retention that comes with it, the scale may go up, but that doesn’t tell us anything about fat. In fact, as we build muscle, this new muscle will help us burn fat faster in the future!

Here’s a real-life example of how the glycogen boost bumped my weight up when I recently started a new workout program in December 2020.

weight gain after increase - 2020 example
You can see the scale went up a few pounds, and it took some time before the weight came back down.

Why It Might Not Be Okay

Although exercise is awesome for the body and is highly recommended, it can be an excuse to over-eat. My personal experience is that I eat a LOT more when I have a regular exercise routine in my life. Part of it may be mental because I might feel like I “deserve” to eat more. Part of it may be physiological because my body is demanding additional nutrition. I have discovered that for myself, I can easily gain weight if I don’t keep an eye on my weight when I begin a new exercise routine.

It may sound obvious, but if you eat more than you burn, you will build up fat stores. If you start eating more because you exercise, you may gain weight, and not just the good kind.

Here’s an example of my weight gain when I started an exercise routine in 2018. I used exercise as an excuse to just over-eat. I used the excuse that I was building muscle when in reality only part of my weight gain was due to muscle. A lot of it was just fat being stored due to me being less mindful and over-eating.

weight gain after exercise - 2018 example
I kept on gaining weight as I continued my exercise routine in 2018, largely because I changed my eating habits.

For some people, exercise can jump-start a person’s weight loss. Their eating habits don’t change much, and they can lose weight relatively quickly with the additional calorie burn boost that exercise provides them. For others, exercise increases hunger, and it can feel like you’re eating the same amount even though you’re really not, therefore exercise won’t help with weight loss at all. That’s why it’s so important to reflect and learn how your body reacts to certain things!

What to Do About Exercise Weight Gain

It’s important to recognize that exercise can lead to water retention, but this is good water retention. It supports glycogen storage, which is a good thing for our body, allowing us to be stronger. I recommend that if you are beginning an exercise routine and you start seeing that this water retention, to just shift your goal, to compensate for the additional water weight.

Don’t worry too much about a weight plateau for the next month, but if you see your weight creeping up, be sure to check your eating habits and ensure you don’t do what I did in 2018 where I kept on gaining weight due to my increased hunger. If you are looking to break a plateau, however, check out this link for ideas.

Definitely don’t give up because you see the weight increase! Weight gain when you start an exercise routine is not a sign that you are failing or doing anything wrong. It is just a natural physiological process.

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