A Guide to How Running Can Change Your Body

You’ve been running for a few months now and you really enjoy this form of fitness. Another perk of running is that you could have sworn your body is looking better from then to now. You wish you had taken some before and after photos, but you didn’t. Can running improve your body, and if so, how?

Running can change your body by bettering your metabolism, which decreases your body fat. You’ll also lose weight and build more muscle, especially in areas like the rear, calves, and thighs. 

In this post, we’ll elaborate further on how running can transform your body as well as discuss how often you should run for the healthiest, fittest you yet. If you’re new to running, then make sure you keep reading, as this post is for you! 

Here’s How Running Can Change Your Body

Less Body Fat

Everybody needs body fat, as the fats within us are crucial for hormone production and nutrient absorption. Too much body fat though means you’re likely overweight or obese. Now you’re at risk of all sorts of health conditions, among them kidney disease, fatty liver disease, osteoarthritis, sleep apnea, some cancers, stroke, heart disease, high blood pressure, and type 2 diabetes.

Body fat is calculated as a percentage. According to this post from the American Council on Exercise or ACE, the average body fat percentage for men is 18 to 24 percent and 25 to 31 percent for women. Men are considered obese if their body fat percentage exceeds 25 percent. For women, they’re obese if their body fat goes over 32 percent. 

Those numbers tell you that the average person is very close to reaching obese territory. 

As a runner, male body fat levels are between 11 and 14 percent and can be as low as five to 10 percent, says Runner’s World. For women, their body fat may be around 16 to 23 percent but can decrease even further to a range of eight to 15 percent.

It’s important to note that fat loss is not the same as weight loss, although losing weight can happen when you start running too. With less fat on your body, you’ll be able to see all the muscle tone you’ll develop from running (more on that shortly). 

Much more importantly, you’ll also be healthier, as you can ward off the conditions that are tied with obesity. 

More Muscle

Most people associate building muscle with putting long hours in at the gym lifting heavy weights. Sure, that is indeed one way to get bigger, stronger muscles, but fortunately, it’s not the only way. Running can also lead to an increase in muscle mass, especially in the lower body.

The reason for that is how muscles form. When you apply stress to the muscle through physical activity, you cause small amounts of damage to your muscles. Your immune system reacts to the damage by healing the muscles. Although it doesn’t happen the first time around, by continuously straining the muscles over the long-term, they get bigger.

When you run, both your vertical and horizontal motion encourages the development of muscles. Vertical motion, in this case, refers to how your feet land as you complete your stride. For each stride, you bear more weight than your own body weight, somewhere in the range of eight to 14 times more.

As for horizontal motion, this is your strides, or how you push yourself forward as you run. The act of moving this way requires lots of muscles, including those from your calves, core, glutes, and thighs. We encourage you to go back and look at this article about all the muscles you use when running, because it really is a lot!

We’ve talked on this blog about how weight loss can plateau, and the same is true of building muscle. When you first get started running, after you find a routine that works for you and you stick with it, you’ll gain muscle and lose body fat, which can make your body look very different. 

However, muscle-building plateaus will probably soon crop up, especially if you’re a more seasoned runner. To keep building muscle, you need to target your fast-twitch muscle fibers. 

Let’s rewind for a minute here. Muscle fibers are your skeletal muscles, and they can be either slow-twitch or fast-twitch. A slow-twitch muscle fiber is one that’s most active when you’re doing steady, consistent exercise with minimized movement. Compare that to a fast-twitch muscle fiber, which is triggered when you use more power but in shorter increments. 

As a runner, you can try adding inclines to your routine or sprinting in short bursts. This will set your fast-twitch muscle fibers alight so you can begin seeing more muscle gained on your runs. 

Where exactly do all your muscles develop? Since running involves your core and the lower half of your body primarily, those will be the areas where you’ll build muscle. Your glutes and thighs could be rock-solid, and your calves may look like those of the athletes you see on TV. 

You might notice some muscle gains in your arms, since you do indeed use them when running, but you’re not going to have big, swole arms like you would if you’re lifting weights at the gym. 

Less Weight

Another way you can change your body through running is weight loss. We recently published a post that mentioned how you can burn between 350 and 510 calories by running for 30 minutes depending on your weight. That information comes courtesy of ACE once again, this time in their Fit Facts report.

At 120 pounds, you burn 11.4 calories a minute. At 140 pounds, it’s 13.2 calories a minute, then 15.1 calories a minute at 160 pounds and 17 calories a minute at 180 pounds. Using that information, let’s calculate how many calories you can burn by running for 60 minutes.

  • 120 pounds – 684 calories burnt after an hour
  • 140 pounds – 792 calories burnt after an hour
  • 160 pounds – 906 calories burnt after an hour
  • 180 pounds – 1,020 calories burnt after an hour

You lose weight when your body burns more calories than you ingest. We’ve proven on this blog a handful of times that running can lead to weight loss. On average, you should expect to lose one to two pounds a week. This might not sound like much, but over the ensuing months and even years, you can lose 10, 20, 30, even 50 or 60 pounds in some instances.

That ACE report concludes that compared to all sorts of other physical activity, including many sports, you burn more calories per minute when running. Whether you want to go down one pants size or several, running is a good way to get there.

Do keep in mind that there can be upsides and downsides to losing weight from running or other activities. Many runners report that their arms get smaller between a combination of the weight loss and fat loss. Women might notice that their breasts shrink, which can be a tough pill to swallow for some ladies.  

Better Metabolism

Here’s something else we discussed on our blog recently. A 2011 report from the journal Medicine & Science in Sports & Exercisedid a study on whether 45 minutes of high-intensity activity could affect a person’s metabolism even after their activity ended.

The researchers gathered 10 participants, all males between 22 and 33 years old. The participants exercised for 45 minutes at a clip. This caused them to burn around 519 calories. Much more importantly, the researchers found that 14 hours after the men were done cycling, they were still burning more calories since they had revved up their metabolisms.

Yes, this study involved cycling and not running, but what seems to matter less is the type of exercise and what’s more important is the vigorousness of the activity. The men that pushed themselves harder had more metabolism benefits.

This goes back to high-intensity interval training or HIIT, which we’ve written about. When you do short but powerful bursts of activity, you kickstart your metabolism even when that activity is long since finished. You can also burn significant calories, which correlates with the study.

How Often Do You Need to Run to See These Positive Body Changes?

You’d love to lose a few pounds, tone up, and shed some body fat, all while boosting your metabolism in the process. Do these health perks require you to run every day? Absolutely not. Exercising daily, whether you’re running or doing anything else, is considered overexercising.

Remember the process we mentioned earlier about how your body builds muscle? You tear the muscles on a nearly microscopic level, then your immune system begins the healing process. Without that healing, muscle growth can’t occur. When you exercise every day, all you do is add to the muscle damage but without the healing. What’s worse is you increase your risk of injury since you’re so fatigued.

Realistically, when you first start running, you want to do it at least twice a week. Then, build onto that, running thrice every week. It’s then that you’ll probably start seeing the bodily changes discussed in the above section. 

As you get more comfortable and familiar with running, add another run to your weekly schedule so you’re running four times each week. Then, start running for five of the seven days. 

These runs don’t have to be consecutive, by the way. If you go for a run about every other day, that’s fine. As long as you’re taking a rest day at least twice a week to recover your muscles (and your energy levels!), then you’re doing everything right.  

Final Thoughts 

Running can tone you up as you lose body fat. You’ll also notice your muscles more since they’ll grow bigger, especially your lower half. Don’t forget the weight loss too, as that’s another way your body will change. You could even improve your metabolism so you’re burning calories when you’re at rest. 

The best change that will come from running is that you will be healthier, and maybe happier too. Many runners find their joy in lacing up a pair of athletic shoes, hitting their favorite trail, and logging their miles. If you too discover that running is your passion, then the above benefits will be the icing on the cake. 

Geoff Southworth

I am a California native and I enjoy all the outdoors has to offer. My latest adventures have been taking the family camping, hiking and surfing.

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