Why Are You Gaining Weight When You Exercise?

So, you want to lose some weight, so you start exercising. You are working out maybe a couple times a week, and you are starting to see results. After a few weeks, you decide to step on the scale. You are in shock when you discover that you have actually gained a few pounds.

This usually happens to most people. In this article, I am going to discuss why you are gaining weight after exercise instead of losing it.

During the first few months of exercising, your body will naturally go through several changes. First, you will go through an initial weight gain and then a secondary weight gain.

Initial Weight Gain

First of all, exercise puts stress on the muscle fibers, causing small micro tears (also called micro trauma, which sounds way scarier than it actually is) and possibly some inflammation around the micro tears. Then the healing response occurs, in which the body retains fluid in order to heal those tears. You may also experience delayed onset muscle soreness (DOMS) 24-36 hours after exercising since that is the body’s natural response to the micro muscle tears and the breakdown in muscle tissue.

You may also gain weight due to how the body provides energy to the muscles. Your muscle cells convert glycogen (aka sugar) to glucose, which is the energy source for your muscles. When you exercise regularly, your body stores more glycogen as fuel for exercising. Since glycogen is stored in water, it has to bind with water to fuel the muscle. This water also adds a small amount of weight. The muscles eventually become more efficient as they familiarize themselves with the routine of exercising. They gradually need less glycogen to maintain the same level of energy output, decreasing water retention. After a few weeks to a month of starting your exercise routine, you will lose the initial water weight gain.

Secondary Weight Gain

After going through the possible initial weight gain and loss, there will be some time before you go through the secondary weight gain, depending on how much excess fat you will lose first. After you lose a certain amount of fat, you will begin gaining lean muscle mass. In other words, you are losing fat, but you are also gaining muscle, which weighs more than fat.


If you gain weight, even when you are exercising regularly, don't think too much of it. It's normal to gain weight after working out for a while. In fact, it's actually good because you are probably increasing muscle, which is making you strong! 💪

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