I’ve been seeing a lot of social media posts lately claiming that running makes you gain weight or wrecks your hormones. Every time I come across one of these statements, it really gets under my skin.

I’ve been running year-round since I was about 15 years old. That’s nearly 27 years of consistent running. It’s been a steady presence in my life through all of its ups and downs, and it’s one of the most important tools I have for becoming the best version of myself.

First of all, the claim that running makes you fat is simply incorrect. By definition, an activity that burns a significant amount of energy cannot directly cause weight gain. That said, I also understand the nuance behind this idea: burning a lot of calories doesn’t always translate to fat loss or even weight loss. I learned this firsthand while breastfeeding my three children. Despite the fact that breastfeeding burns a substantial number of calories, I actually tended to gain weight during those periods.

When we look at this from an evolutionary perspective — which I often do (and which, by the way, aligns with my Christian worldview and supports my belief in intelligent design) — it makes perfect sense. It wouldn’t be beneficial for a woman who is nourishing two people to lose excessive fat and risk starving both herself and her baby during times of scarcity. In fact, research shows that even though breastfeeding burns calories, a woman’s body is designed to protect fat stores as a survival mechanism. This gave women an evolutionary advantage, and during times of famine, women survived better than men.

When women are breastfeeding an infant, we have additional mechanisms that are working to ensure survival of both. The hormone prolactin, which is responsible for milk production, also promotes appetite and can prevent the breakdown of fat. I can remember feeling hunger like I’d never felt before when I was breastfeeding my oldest. I remember stuffing energy bars in my bathroom drawers so in the middle of the night when I was up with her, I could satisfy my extreme hunger.

Additionally, low estrogen (which can suppress ovulation, because again, you’re already providing for one infant, your body wouldn’t want another pregnancy yet) can affect fat distribution and reduce metabolism. Then there’s the fact that most new moms are not getting a lot of sleep and often experience higher stress levels, increasing cortisol which also promotes fat storage, instead of breakdown. So I often gained weight the first 6 months of breastfeeding with all of my kids!

The claim that running can make you fat, is based on the fact that intense cardio is a stressful event. As such, it can increase cortisol, which encourages fat storage instead of fat breakdown, but this claim over simplifies a very complex process.

Yes, high intensity cardio exercise can temporarily increase cortisol levels. So again, we turn to evolutionary biology. The thing is that exercise is one activity that humans are highly adaptive to. And we are incredibly well suited to long distance endurance events. Think about our ancestors who had to hunt for food. They often had to run animals to exhaustion in the heat of the day. This was particularly helpful in the African savanna’s where humans would run the animals in the open sun until they would collapse from exhaustion.

What gave us these advantages? Humans can sweat, unlike most other mammals that can only pant to cool themselves. We also are not covered in thick body hair, which allows our skin to cool faster. Thinking back to the breastfeeding example, where it doesn’t make sense for a woman to lose fat storage when she’s feeding two humans, it likewise wouldn’t make evolutionary sense for humans that could run as part of supplying food to store excess body fat that would surely slow them down.

Running can temporarily increase cortisol (the stress hormone) which can free up energy to be able to perform the work. Very long running sessions or high intensity running can increase the stress on the body in the short term. It’s actually chronic high stress (from lifestyle, not enough available energy, etc) that can cause fat increases.

If someone inactive starts an exercise like running for the first time, it can increase stress levels over activities like walking. That’s why I recommend if someone is just starting out, they start with a walk/run plan that gradually lets the body adapt to the stresses of running, like a couch to 5K training plan.

Humans bodies are wired to respond effectively to the physical stresses we place on it. When high intense bouts of running are combined with proper rest and recovery, the body is able to adapt and increase our fitness, or our ability to tolerate load.

In the short term, after running, people might find the number on a scale going the opposite way they want. This is because of the adaptations your body is making to help you tolerate the load in the future.

For example, your muscles start storing more water and glycogen (energy), which can make your body weight increase. It’s important to understand that this is not fat, it’s water and available energy stores. Which is one of the reasons, if you are trying to lose excess body fat, and you start exercising, I recommend not weighing yourself often because it can psychologically be defeating to see the scale going up.

Here’s what can happen to your body that can positively impact your body composition from regular running:

• Improved insulin sensitivity (reduced insulin sensitivity is one of the biggest causes of fat gain today)

• Your body stores less fat and burns more glucose (a sugar) effectively

• Running burns calories, not just when you’re running, but also improves your resting metabolic rate (overall metabolism)

• Your body adapts to be better at using both fats and carbs for fuel

• Your body adapts to better regulate hunger hormones (again, having excess fat would not have helped our running ancestors)

• Long term aerobic activity reduces visceral fat (the deep, more harmful fat)

• Running can change your overal body composition, especially when combined with strength training to have greater muscle and lower body fat

When you’re well adapted to running, it no longer causes high cortisol spikes. For example, if I go for a short recovery run where I’m just running easy it’s not really increasing my stress. My body is adapted to exercise, so the stress load is not more than going for a light walk for someone who doesn’t exercise.

Your recovery system (the parasympathetic system) becomes stronger, so cortisol spikes return to baseline faster. This helps you handle not just exercise stress better, but ALL stress better.

So while starting an exercise like running can temporarily increase stress and even make you gain weight on the scale, long term it improves your body composition and can help you reduce your stress levels overall, leading to fat loss over time.

The next claim, that running can mess with your hormones is rooted in the same logic.

If you’re always doing high intensity or excessive cardio (like always running for an hour or more every day) it can affect your hormones negatively.

This can actually breakdown muscle and suppress immune function. It can impair the thyroid, and promote fat storage.

In women, high training loads with inadequate fat levels can cause amenorrhea or cessation of menstruation. By the time amenorrhea starts estrogen and progesterone have dropped which can lead to bone loss, mood dis regulation and decreased fertility

In men, high training loads with inadequate energy availability can reduce testosterone which likewise can reduce mood, energy and muscle mass.

The body actually slows down metabolism when energy requirements are not consistently met to conserve energy making you feel tired, cold intolerant and can make you gain weight.

I believe this is where the claims about running making you fat and disrupting your hormones comes from. Often these claims encourage walking and weight training over running.

There is nothing wrong with walking or weight training as effective exercises to reduce body fat and improve overall health and body composition. Not everyone likes running and individual body differences can make the stress of running harder to tolerate. I’m certainly not suggesting that everyone should run or that it’s superior to other forms of exercise that other individuals enjoy more. The best exercise for an individual is going to be one they enjoy and will continue to do regularly.

Unfortunately, for many athletes in their younger years, running was given as a punishment and so people naturally associate running as hard and even painful (no pain, no gain) instead of a relaxing activity. I’ve heard someone say that running doesn’t count unless they’re sweating profusely and miserable. I don’t know about you, but that doesn’t sound like something I’d like to do very often.

You can see that the claims running makes you fat or disrupts your hormones are disingenuous.

Starting running slowly and ensuring proper rest and recovery as well as adequate nutrition can absolutely improve your overall health and body composition without sacrificing your hormone health.

Regular Running, especially compared to other lower intensity activities can benefit an individual by:

-improving heart efficiency (lower resting heart rate)

-reduces the risk of hypertension (high blood pressure)

-improved VO2max (maximum oxygen uptake) associated with longevity and running improves this significantly more than walking

-Increased bone density (the force of running on the bones causes them to adapt by increasing density)

-Stronger muscles especially in the lower body, which has the largest muscle groups

-Increased tendons and ligament strength

-Better joint health (which is also another false claim I see a lot of, that running bad for your joints, especially knees) running actually improves cartilage

-Muscles become more efficient at using glucose (reduced insulin sensitivity)

-better fat metabolism

-Immune system improvements (regular running increases immune surveillance)

-Improved stress resistance

-Improved resting metabolism

-Improved balance and proprioception.

-Enhanced brain function (promotes growth of new brain cells)

-Better sleep

-You burn more calories per minute running than by walking or weight training so if you’re short on time, running is an efficient way to burn a lot calories

-Running improves mitochondrial function in your cells

-Can increase your lifespan and reduce your cancer risk

-When done correctly without overtraining can help women balance estrogen and progesterone

Psychological Benefits:

-Improved mood

-serotonin and dopamine is boosted

-Improved memory

-Promotes growth of new brain cells

-Creates feelings of accomplishment and can boost resilience

Running can be a very mentally challenging form of exercise. I do love running and the many benefits I derive from it, but not every run is an enjoyable experience and some days I absolutely dread doing it. These are typically days where it’s freezing or there’s tons of snow or it seems like no matter which direction you’re running in, the wind is in your face! Sometimes when it’s a downpour and it’s already cold outside I sit there trying to talk myself into just getting out there.

The thing is, when I do, I always feel so much better and I find I feel even more accomplished the harder the conditions were. I heard it said that when you show up for yourself when it’s tough, you’re building trust within yourself. When life throw’s unexpected curve balls (and it does) you can look back on these difficult things that you got through and have confidence in yourself.

Sometimes with my kids who are too young to have built a ton of resilience yet will get so defeated at the first sign of difficulty. It’s a skill you need to practice, and running truly drives this lesson home.

Our society has become increasingly more comfortable. Yet it has not made us any happier and in fact, the mental health crises continues to just get worse. Running can be hard and uncomfortable, but for humans, who have been highly adaptable to uncomfortable environments for all our history, perhaps regularly making yourself uncomfortable can help you appreciate the things we often take for granted. I know for me, grinding out a long run in the bitter cold of winter makes me appreciate a hot showers and a warm cup of coffee so much more. And a run in the pouring rain can actually be fun once you get over the fact that you’re going to get wet.

I don’t remember many of my runs in college in detail, they mostly all just blur together but I do remember some of the harder runs in terrible weather that I made it through with my friends and teammates. My friend has a photo of us still in her home after a long run where the snow was coming down in our faces so hard that our eyebrows and eyelashes were completely covered by chunks of ice! We could barely even see, but we did it!

It know running isn’t for everyone, but I don’t want people to not do it because of poor information circulating on social media. If you enjoy it and want to do it, it absolutely can help you reach your health goals. You do need to be careful not to do too much too soon, or to overtrain without enough fuel. These mistakes CAN absolutely derail your plans. We adapt to progressively higher loads, so you should always build up mileage or training load slowly, a good rule is no more than 10% increases week over week.