The Ugly Truth of Half-Marathon Training and Weight Loss

I began running about 7 years ago solely with the intention of aiding in my weight loss journey. As I incorporated the extra cardio into my new, healthy lifestyle, it definitely helped me shed some of those pounds. And I was ecstatic!

But when the weight loss seemed to plateau, I knew it was because I was becoming efficient at running. My body had adapted to what I was asking it to do. I knew that I needed to change up my workout in order to “surprise” my body back into weight loss. I thought increasing my mileage would do the trick and help me drop a few more pounds… Unfortunately, that is not always the case. 

I thought training and running for a half-marathon would be a surefire way to drop some additional weight. Spending an hour to two hours running each weekend, plus all the weekly training runs and workouts must torch some major calories, right? 

In a sense, the answer is yes — but that doesn’t always mean weight loss. I am reminded that high levels of training does not mean weight loss this half-marathon season. Once again, I was lulled into the idea that training and weight loss go hand in hand.

But the truth is (according to the scale) I have actually gained a few pounds.

But Why Does Weight Gain Happen (for some) During Training?

There are a few reasons why weight gain occurs during half-marathon or marathon training. Some of these reasons may be obvious while others are a little more mysterious. And as always, each person is different and may have a few different reasons why they are experiencing weight gain during the training cycle. 

*Please also remember, I am not a doctor. The information provided here is what I have gather from my own personal experience and through personal research while frustrated with the lack of weight loss. Your own experiences may differ from mine.* 

The first reason for weight gain comes down to a simple word: RUNGRY.

The more (some) people run, the hungrier they become. And while it’s true that some of that energy needs to be replaced in the form of more food, we have a tendency to over-estimate how many calories we actually burn while running. This over-estimation results in over-consumption of calories post run. 

The reverse can also happen. Running sometimes decreases the appetite, resulting in a calorie deficiency. Although a calorie deficiency is necessary for weight loss, too few calories can result in the body going into “starvation mode”, slowing the metabolism and weight loss.

Another reason that people can see “weight gain” from half-marathon or marathon training is the fact that they are actually gaining muscle. And while this type of gain is actually very beneficial, it can be disheartening to see the number on the scale rise. 

Muscle indeed weighs more than fat, but it also burns more calories to maintain and that weight comes in much smaller packages.

For those more visual: 5 pounds of fat can be represented with 3 grapefruit; while 5 pounds of muscle are represented by 3 tangerines. Your body composition might be changing, even if the scale is not. 

Personally, I feel like my leg muscles are WAY more defined during this training session versus last year’s training. So, even if the scale is refusing to budge, I am seeing some non-scale changes in my own physique.

You may also see the scale creep up as your mileage increases due to your bodies own protection mechanisms. The human body is an incredible phenomenon. As a person starts training for endurance type feats, the body adapts.

It starts to learn to store more glycogen (or carbohydrates — which is the main form of energy the body uses during exercise). While storing more carbohydrates to burn, the body also stores more water. More water = more weight. And although this isn’t a lasting “weight gain” it can prove frustrating and discouraging to those hoping to reduce during the training process.

Half-marathon and marathon training is also highly stressful on the body. The long hours of training and running, pushing the body to the limits and beyond can start to take a toll.

Stress is another reason people can see weight loss stale during half-marathon or marathon training. The body’s stress response releases hormones. In turn, these hormones activate the release of glucose(sugar) and fat into the bloodstream. These nutrients provide energy the body needs to react to the stressor quickly. 

If the body remains in a constant state of stress, it tries to replace the energy that was depleted by adding more fat tissue. More fat tissue results in more weight gain and an expanding waistline. 

Rest days are SO important to let the body reset. The body needs  to repair, heal, and recharge in order to stay functioning at such a high level. 

With rest in mind, the lack of sleep can also cause weight gain while half-marathon or marathon training. During training, one is logging a lot of hours running. And with our busy lifestyles, cutting back on sleep seems like the way to fit everything in.

Unfortunately, cutting back on sleep will not help you to reach your weight loss or marathon goals, even if you cut sleep for a workout. Losing sleep not only affects the quality of your workouts, but it also affects what  kinds of food you crave. 

Overall, there are many reasons as to why you might not be losing weight while half-marathon or marathon training. Before you decide to ditch the distance, consider these tips.

  • Measurements: Take before, during, and after measurements. It is the most accurate way to judge how your body composition is actually changing.
  • Pictures: Along with a tape measure, taking before, during, and after photos will really illustrate your progress. 
  • Feel pride in what your body is able to do (even if it is a few pounds heavier).
  • Enjoy the experience! Less than 1% of the population has done what you are setting out to do.
  • The training doesn’t last forever. Neither will your weight gain.

It amazes me every time I complete a long distance run at what my body is able to accomplish. Even if I am not at my “goal” weight, I feel strong and healthy. And that is exactly how I want to feel. 

  1. What’s your go-to food to eat when you are “Rungry”?
  2. Have you experienced any training and weight loss?
  3. What was your primary motivation to start running?