Why Does Running Make Me Gain Weight

Running is often considered one of the best exercises for weight loss. However, it is not uncommon for some individuals to experience weight gain instead of weight loss when they start running. This can be frustrating and confusing, especially if you are putting in the effort to exercise regularly and eat a healthy diet. In this article, I will delve into the reasons why running may cause weight gain and share some personal insights and commentary along the way.

Caloric Intake

One of the main reasons why running can lead to weight gain is an increase in caloric intake. When we engage in physical activity, our bodies burn calories for energy. This can create a false sense of entitlement, causing us to overestimate the number of calories burned during a run. As a result, we may consume more food than necessary to compensate for the calories burned, leading to weight gain.

On a personal note, I’ve fallen into this trap myself. After a long, intense run, I would often reward myself with a high-calorie treat, thinking that I had “earned” it. However, I soon realized that my indulgences were surpassing the calorie deficit created by running, leading to weight gain rather than weight loss.

Muscle Gain

Another factor that can contribute to weight gain when running is an increase in muscle mass. Running is a high-impact exercise that engages multiple muscle groups, particularly in the legs. Over time, as you continue running and challenging your muscles, you may notice an increase in muscle size and strength.

While muscle gain is generally a positive outcome of running, it can lead to weight gain on the scale. Muscle is denser than fat, meaning it takes up less space but weighs more. So, even though your body composition may be improving with more muscle and less fat, the number on the scale may not reflect this change.

Fluid Retention

Fluid retention is another potential explanation for weight gain during running. When we engage in exercise, our bodies may retain water to aid in recovery and repair damaged tissues. This can result in temporary weight gain due to increased water retention.

Personally, I have noticed fluctuations in my weight after intense running sessions. These fluctuations are often related to water retention, as my body holds onto extra fluids to support the healing process. It’s important to remember that this weight gain is temporary and will subside as your body recovers.

Increased Appetite

Running can also increase appetite, causing us to eat more than usual. When we engage in prolonged aerobic exercise like running, our bodies require additional fuel to sustain the activity. This can lead to an increase in hunger and cravings, making it harder to maintain a calorie deficit.

I have experienced this firsthand, feeling ravenous after a long run and reaching for larger portion sizes or unhealthy snacks. It’s essential to pay attention to your body’s hunger cues and make conscious choices when it comes to refueling. Opting for nutrient-dense foods that provide sustained energy can help prevent excessive weight gain.


In conclusion, running can lead to weight gain for various reasons. Increased caloric intake, muscle gain, fluid retention, and increased appetite can all contribute to this phenomenon. It’s essential to be mindful of your eating habits, listen to your body’s hunger cues, and make informed choices when it comes to refueling. Remember, weight is just one measure of fitness, and overall health and well-being should be the ultimate goal.