Running But Not Losing Weight? 7 Potential Reasons Why

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There are many excellent physical and mental health benefits of running, and each runner may be compelled to start running for a different subset of these benefits.

Among the most common reasons to start running is to lose weight.

However, some runners find that they are running but not losing weight, or worse, they may be gaining weight from running every day.

Of course, if you are running but not losing weight, it can be extremely frustrating, if not even confusing. After all, isn’t running supposed to help you lose weight?

In this article, we will discuss 7 reasons why you might be running but not losing weight or are even gaining weight running despite training every day.

Let’s jump in! 

A runner looking at their watch, running but not losing weight.

7 Potential Reasons You Are Running But Not Losing Weight

Here are some potential reasons why you’re not losing weight even though you’re running or you find yourself asking, “Why am I gaining weight from running every day?”

#1: Your Watch Is Overestimating Your Calorie Burn

One of the primary reasons why you might be running but not losing weight or even gaining weight by running is because you are overestimating the number of calories that you burn running.

Particularly if you use a fitness watch, be at an Apple Watch, Garmin watch, or another smartwatch, or you are using the treadmill calories as a reliable metric, you might be doing “calorie math“ with a higher caloric expenditure than the actual number of calories you burn running.

Many fitness watches and treadmills drastically overestimate the number of calories you burn while running.

Three people running.

If you are gaining weight while running every day or simply are not losing weight running, but you’re using technology to tell you how many calories you burn while running, you should start adjusting the number of calories your watch or treadmill report that you have burned.

A study published in 2018 compared the number of calories burned on an elliptical machine according to the calorie counter versus the actual number of calories burned according to indirect calorimetry (the gold standard for measuring energy expenditure).

It found that some elliptical trainers overestimate the number of calories burned by as much as 130 calories over the course of a 30-minute workout. 

Similar overestimations can occur with treadmills and fitness watches.

A good rule of thumb is to decrease the calories your treadmill or watch say you burn running by 15-20%.

For example, if your Apple Watch reports that you burn 500 calories running, assume that you have burned closer to 400.

A large portion of steak.

#2: You’re Eating Too Much, Or Your Portion Sizes Are Too Big

In order to lose weight, you need to be in a caloric deficit, which involves eating fewer calories than you are burning (your total daily energy expenditure (TDEE)).

For every pound of fat loss, you need to create a caloric deficit of 3500 calories.

Even though it is often easier for people to wrap their heads around the concept that what you eat matters when you’re following a weight loss diet, how much you eat arguably matters just as much.

Even if your diet consists of primarily “healthy“ foods, you may be running but not losing weight, or even maybe gaining weight running every day if you are simply eating too much food and exceeding the appropriate portions for your body size, activity level, and overall caloric needs.

Consider peanut butter, for example. Natural, unsalted peanut butter is generally considered to be a healthy food.

It provides heart-healthy fats, some protein, and some fiber, along with essentially no sugar and very little sodium when choosing unsalted varieties. There are also numerous vitamins and minerals in peanuts and peanut butter.

However, peanut butter is a calorically-dense (energy-dense) food, which means that there are a lot of calories in a small volume of food.

According to the USDA, a typical 2-tablespoon (32-gram) serving of peanut butter provides about 190 calories.

Therefore, if you are trying to run for weight loss and are making efforts to clean up your diet, it is important to measure your serving sizes because 2 tablespoons is not all that much peanut butter, and many people end up estimating or eyeballing the portion size of peanut butter and overeating their calorie goals.

Check out our TDEE Daily Calorie Calculator to better understand your own daily caloric needs.

A person seated, working at a table.

#3: You Are Sedentary the Rest of the Day

Many runners work extremely hard during their running workouts along with any strength training or cross training that they do, but the majority of the day, they are sitting down or essentially inactive.

Known as non-exercise activity thermogenesis (NEAT), physical activity in your daily life can contribute a significant number of calories to your total daily energy expenditure.

However, if you are using an online total daily energy expenditure calculator or trying to estimate how many calories you need per day, you might be overestimating your actual energy expenditure because you are sitting much more than you think you are.

Consider getting a standing desk and trying to work more non-structured physical activity into your day. If this isn’t possible, you may need to reduce the ballpark number of calories you are assuming you need to eat in a day.

#4: You’re Not Refueling After Your Workouts

When you’re running for weight loss, there is a tendency to want to cut back on calories.

For this reason, many runners forgo a post-workout snack, particularly because it’s common to lose your appetite or even feel nauseous after running.

A runner smiling, holding a protein bar.

However, fueling well within 15 to 30 minutes after your workout is over can help give your muscles the protein and carbohydrates necessary to replenish glycogen and start rebuilding and repairing muscles.

A post-workout snack can also help stave off a big spike in hunger later on, helping control your caloric intake when you’re running to lose weight.

Try to eat 20 to 25 grams of protein in your post-run snack, and then repeat the same dosage in your next meal after you have cooled down and moved on with your day.

Immediately after the long run, you might not feel like eating a protein-rich food such as chicken, salmon, tuna, or ground beef, but you can have a protein bar, protein shake, or high-protein food such as nuts, seeds, or even whole eggs.

A single large egg provides about 6 grams of protein. You will also get sodium, vitamin D, minerals, and some antioxidants to help combat inflammatory damage.

A daily food log list.

#5: You’re Not Aware of How Much You’re Eating 

Studies have found that we are often unaware of how much food we are actually eating or may underestimate our caloric intake.

Writing down everything you eat can help bring awareness to your caloric intake.  

Thus, if you believe you’re eating well but are running yet not losing weight, keeping a food log can be helpful to bring awareness to how much you are actually eating and help you be more mindful and deliberate in your food choice and portion sizes.

Indeed, research has shown that keeping a food log can result in greater weight loss.

#6: Your Workout Routine Isn’t Varied Enough

The body adapts to our exercise routine, so if you are running but not losing weight, it might be that your body has become more efficient with your workouts.

This is particularly common for people who run at a steady pace every day, run the same route every day, or have very little variety in their training.

Consider incorporating intervals, hill sprints, hillier runs, long runs, short runs, and tempo runs to challenge your metabolic system and prevent your body from becoming too accustomed to your running routine.

This will help you burn more calories while you run so that you can keep losing weight running.

A very small salad, fork and knife.

#7: You’re Not Eating Enough

If you are running for weight loss and cutting back your calories too significantly, the body can perceive a relative starvation mode and will initiate survival mechanisms to slow down your metabolism and reduce your energy expenditure.

Make sure that you are eating enough calories to support your training.

You should not be trying to lose more than 1 to 2 pounds per week, which means that you cannot exceed a caloric deficit of an average of 500 to 1000 calories per day, and this is still very aggressive.

It might be that your body needs a break from caloric restriction if you have been dieting consistently for a long time and running without losing weight. 

Consider increasing your calories by 10 to 15% for a couple of weeks, and then try cutting back again.

For more information about how to calculate how many calories you need as a runner, check out our guide here.

A calorie counter nutrition facts sheet, surrounded by fruits and vegetables.
Photo of author
Amber Sayer is a Fitness, Nutrition, and Wellness Writer and Editor, as well as a NASM-Certified Nutrition Coach and UESCA-certified running, endurance nutrition, and triathlon coach. She holds two Masters Degrees—one in Exercise Science and one in Prosthetics and Orthotics. As a Certified Personal Trainer and running coach for 12 years, Amber enjoys staying active and helping others do so as well. In her free time, she likes running, cycling, cooking, and tackling any type of puzzle.

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