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Cortisol | How Does It Affect Weight Loss

Cortisol | How Does It Affect Weight Loss

Whether we have goals to lose 20 lbs on the scale, drop a few sizes or lower our body fat to better show our muscles, dieting techniques and fads will always be around. From the liquid diet to the ketogenic diet to the paleo diet, all promise one thing: the body you’ve always hoped for. With so much emphasis put on counting calories, timing your meals to the minute and the idea that “abs are made in the kitchen”, most individuals get a sort of tunnel vision and completely devote their weight loss goals to how they eat. And while what you eat and when is going to impact how much weight you lose or how much fat you burn, some would argue training, sleep and the rest of your day is just as important.

This rationale comes from the idea that your diet can be perfect, with no cheat days, no simple sugars, no trans fats, high protein, high poly and monounsaturated fats (healthy fats), low carbs on days with less workout intensity, 100% daily recommended intake of all vitamins and minerals, a daily deficit of 500 calories, etc.… and lose no fat whatsoever. What you don’t know is the rest of the variables in their life.

A stressful night job, high caffeine intake, long fasted cardiovascular workouts on top of high rep, tedious weight training. What comes of these issues is a pesky little hormone known as cortisol. In this Two Part article I will discuss:

? What is cortisol?

? Why we need it

? How to control/minimize it

Hopefully this will help change your mindset to focus on the bigger picture when it comes to weight and fat loss.

What Is Cortisol?

Whenever we wake up, need to eat food, exercise or are in an overall stressful situation, our body releases a few different hormones to help regulate the stress and ensure survival. Produced in the adrenal glands above the kidneys (and slightly in the hippocampus), cortisol, norepinephrine, and epinephrine all work to produce a survival instinct known as “fight or flight”.

Norepinephrine shuts down your pancreas to stop the production of insulin, allowing your body to be able to easily use blood glucose (blood sugar) to fight or run from the stressor. Because with insulin production your body would shuttle any blood glucose into fat storage or glycogen stores to be used later. And when we are running from a predator we aren’t too worried about storing energy for later, our body wants us to use it immediately to make sure of a quick escape.

Epinephrine slows the blood flow to your stomach and intestines, slowing digestion and effectively preventing any kind of bowel movement. Again, this happens because when we are fighting or running from a predator, our body isn’t worried about wasting energy on digesting foods or bowel movements. It would much rather concentrate all your energy to the threat in front of you.

Cortisol controls both of these hormones, telling your body when to produce them and when to stop producing them. It also tells our body to wake up in the morning, but most importantly cortisol determines which ingested substances in our body are used as energy. Meaning if we just digested a steak and we face a sudden stressor, instead of the protein in that steak getting broken down into amino acids to be used for many reactions in our body (most importantly for us athletic folks, muscle protein synthesis), it will be broken down into glucose to be used as quick energy.

The same goes for fat (with carbs already serving this purpose whether our bodies are stressed or not). Known as gluconeogenesis, out body really doesn’t want to have to break down proteins and fats into glucose, because it is a long and difficult process for the body (unless you are in ketosis, but that is a completely different story). Our body would much rather use simple carbs to fuel our body as they do not need to be broken down much at all to become blood sugar, than using proteins which are ideally broken down into essential amino acids and fats for hormone regulation as well as absorbing fat soluble vitamins.

ketogenic diet


At this point you might be asking, “But we haven’t had to run from predators regularly in thousands of years, why should we have to worry about all this anymore?” Which is a very good question! We have evolved to be above the food chain in a rather quick amount of time, we have effectively beat our physiological evolution meaning our bodies still react to stress as if we were running from a predator or starving to death. And for our ancestors, it wouldn’t be rare to go days without eating, nights without sleeping and a still have to do a lot of running and lifting.

When this happened, they wanted their bodies to use all available food for energy so they could catch their next meal, they wanted their cortisol to be high keeping them up at night to allow them to hunt prey at night and they wanted their digestion to shut down so they could go longer without eating in case they couldn’t find food for days.

And while this might be a lifesaving process for our ancestors, for us elevated cortisol means sleepless nights, more fat storage, insulin resistance and constipation among other negatives. Sure we might have the occasional situation where we have to fight or run from a threat to protect ourselves, but in our modern lives this almost never happens.

But what does happen is night shift jobs, extreme diets, and very intense workouts on a daily basis, which is pretty easy for our bodies to interpret as a life threatening stressor. Our mind knows why we are eating 1500 calories a day or doing a two hour fasted run, but to our body all it knows is, “stress on the body: raise cortisol”.


Cortisol in the Real World

If you’re working the night shift this is going to have an affect on your body. A job that goes from 8pm to 8am, will signal to your body that you’re either looking for food all night or escaping a predator, increasing cortisol production till you can get a full night of sleep (preferably when the sun is down).

Two hour long WOD’s that consist of heavy lifting followed by running? To your body this means you’re working to build a shelter or running from a predator/running to catch prey to eat, putting heavy stress on your body and, you guessed it, increasing cortisol (which happens to an even sharper degree if the workout is fasted).

Starting to see a trend? Even just one of these stressors a day will put your body in survival mode, halting progress in the gym, weight loss on the scale and sleep at home. Most of the time our stressors would be acute, such as starving for a day or two, running from a predator for one night and so on. But in our modern lives are we being constantly stressed even more than before. As I stated earlier, cortisol can save you in a life or death situation, but when we are purposefully starving our bodies daily for months at a time, consistently getting less than 6 hours of sleep every night, and pounding our bodies with workouts, cortisol becomes elevated almost 24/7.

Because of norepinephrine’s ability to stop insulin production, this can effectively stop your fat loss and even lead to fat gain in a calorie deficit. Because insulin’s job is to shuttle unused glucose into the cells as glycogen, this no longer happens and instead all the glucose in your blood goes into fat storage if not used. Epinephrine has a different, but equally as negative reaction in the body when chronically high.

Due to its ability to stop the digestive process and intestines, your food will more than likely not get fully digested. Meaning you will not be absorbing all the vitamins and minerals you are consuming, as well as less digestion of fats, proteins and carbs. Leading to constipation, food fermenting in your intestines (causing flatulence) and less energy/testosterone/muscle protein synthesis from under digested foods.

benefits of weight lifting

The Dangers of Elevated Cortisol Levels

The master of all the stress hormones, cortisol, is just as bad when it is chronically elevated. Besides its purpose to produce norepinephrine and epinephrine, it is the main force to wake us up in the morning. Cortisol in the least stressed out individuals is still peaked first thing in the morning, to help wake us naturally. But when cortisol is elevated throughout the day and into the night, it becomes increasingly difficult to sleep. Testosterone is also lowered because when we are stressed, our body is less concerned with procreating and more concerned with reducing the stress.

What this means for chronically stressed individuals is low drive, power output, libido and gains in the gym. And just when things seem like they couldn’t get worse, high cortisol can lead to a condition known as Cushing’s syndrome. Symptoms of said disease include rapid weight gain to the torso and face, high blood pressure, osteoporosis, mood swings, easily bruised skin, and more. While Cushing’s isn’t very likely unless medicating with a corticosteroid, it can still develop in rare cases. I have barely scratched the surface of symptoms that can occur from chronic stress, and hopefully I have sufficiently informed you of why it is in your best interest to keep your stress down as much as possible!

Take Home Message

When it comes to fitness and nutrition we sometimes get carried away and become too focused on training hard every day, eating clean and very little every day, and so on. Every once and awhile it is imperative to take a step back, and look logically at the other aspects of our lives that are just as important for us to reach our goals. To put it all in a nutshell, our ancestors needed stress hormones for survival, now in the 21st century our body still reacts to stress the same way. What this means for us trying to lose weight or stay active is that we must: get adequate sleep, proper recovery time, a healthy and nutritious diet, as well as regulating our training to keep it as stress-less as possible.

Our articles should be used for informational and educational purposes only and are not intended to be taken as medical advice. If you’re concerned, consult a health professional before taking dietary supplements or introducing any major changes to your diet.

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Billy Galipeault

Billy Galipeault

Writer and expert

Billy is passionate about all things fitness and nutrition, with an emphasis on muscle and strength building. He's currently serving active duty in the air force, while building his body muscle by muscle in his free time.

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