Your body is an amazingly complex system of interconnected processes, chemical, neurological, and mechanical, that can all shift in different directions. Thousands of hormones, nervous systems, and other biological happenings that can be turned up or down in an overwhelming array of combinations.
However, very few of these systems are really independent. You can get a rise in, for example, insulin, by tasting some sugar. But that rise in insulin will never come by itself. That insulin surge will affect many other systems in your body in many complex ways.
You could spend a lifetime trying to unpack all these connections, and that would be interesting, but you might not have time or energy or aptitude for doing so. Luckily, a lot of these systems are organized in some ways that are not terribly difficult to grasp.
Now of course everything in this post is going to be a simplification. But it's a useful simplification, and most of the time most of these systems behave more or less the way I'm going to describe. So while this way of thinking about your body won't capture every possible condition or disease state, it will provide a really great beginning to understanding how your body works.
Instead of trying to figure out the ins and outs of every single hormone and biomarker separately, we're going to put them in two rough categories: sympathetic and parasympathetic.
Put simply, the sympathetic system is the one that gets activated in fight-or-flight situations. When you're anxious, under stress, or under threat, a whole bunch of neurological and hormonal things happen to help you survive the immediate danger. They're all complex and unique flowers, but for the sake of this post we're going to lump them together.
The parasympathetic a system is the other side of the coin. It's the set of hormones and nervous impulses that are firing and elevated when you're relaxed and safe.
It's not a case of all one or all the other. Your adrenaline levels don't drop to zero when you're relaxed, for example. Think of these things as lying on a spectrum. At any given point in time you're either towards the parasympathetic (relaxed and happy) end OR towards the sympathetic (scared and anxious) end or somewhere in the middle. No single hormone or organ is going to give a complete picture of how sympathetic or parasympathetic you are, so we're going to be using some inexact language to describe this spectrum.
It's not a case where you're supposed to be always on one end of that spectrum or the other. It's normal and healthy to get sympathetic sometimes. But, and this is NOT an idea original to me, we evolved to spend most of our time on the parasympathetic end (chillin'), and dip into the sympathetic end only for brief (and probably intense) periods when we were in danger - for example, when being chased by a wild animal. The sympathetic state isn't exactly bad for you, but it's all about sacrificing long term well being for short term survival capacity. In fact, the only way to increase your overall capacity - to get stronger and more fit - is really to push yourself into sympathetic states for controlled periods of time.
The danger comes when we spend too much of our lives in a chronic sympathetic state. When you're stressed all the time there aren't enough chances for your body to recover and rebuild and heal, and that's bad in all sorts of ways.
Here's a second part of this principle that is really, really important: the way your body puts you towards sympathetic or parasympathetic is dumb. REALLY DUMB. As in not sensitive to context AT ALL.
What I mean is, your body tends to lump all the inputs and outputs of these systems together. So, for example, having high blood sugar (sympathetic response) is a GOOD response to suddenly seeing a hungry bear (a sympathetic stimulus), because you want a lot of glucose swarming around for you to use while running from the bear. But it's a TERRIBLE response to seeing your angry boss - there's nothing useful about that glucose in that situation unless you're inclined to get into a fistfight with your boss. And that extra sugar could be doing all kinds of damage, especially if your boss is always angry with you and your blood sugar is regularly elevated.
So if we want to maximize health and well being we have to manipulate our body's response. Simply put: your body, left on its own, is remarkable, but in many ways does not handle modern life very well.
In order to do that, we have to be aware of what makes us more sympathetic, what makes us more parasympathetic, and when we want them.
What pushes us towards the sympathetic state?This is an incomplete list, but a lot of things can push us towards either end of the spectrum. I don't think any of these will be surprising, but there's something I find very interesting about putting the list together and looking at the whole thing.
- Stress - anxiety about life, jobs, relationships, hardship, and also any kind of life change (good or bad), worrying about one's responsibilities.
- Intense exercise (The more intense, and longer the duration, the deeper into sympathetic state it drives you).
- Sleep deprivation (and possibly getting too much sleep).
- Sleeping at the wrong time (sleep/wake cycles out of sync with the sun, like night shift workers).
- Caloric deprivation (not eating enough) or nutritional deficiencies (not eating enough of something in particular).
- Pain (for example, from some chronic injury, like a bad back).
- Social isolation (no friends).
- Excessive stimulant consumption (caffeine, crystal meth, etc.)
- Certain kinds of music (think speed metal).
What pushes us towards the parasympathetic state?
- Sufficient food/nutrient intake.
- Low level physical activity - stretching, long slow walks, especially in nature.
- Moderate intellectual stimulation.
- Low to moderate alcohol consumption.
- Sufficient rest.
- Other kinds of music (whatever they play in elevators).
These are not complete lists, obviously, and the impact of each of these is probably going to vary from person to person. Some people turn into happy noodles after an hour of yoga, others just feel uncomfortable. You have to figure out for yourself which activities work best for pushing you in one direction or the other if you want to control your own parasympathetic state.
Why is it important to be more or less parasympathetic? Well....
What are the effects of being more sympathetic?
- Higher heart rate.
- Higher performance (run faster, jump higher).
- Higher blood sugar; poor blood sugar regulation.
- Compromised immunity (don't fight infections well).
- Poor recovery from workouts.
- Fat accumulation and systemic inflammation.
- Better concentration.
- Less creativity/ poor higher level thinking.
- Poor digestion.
- Stimulate adaptions (muscle growth, increases in endurance, etc.).
- More regular heart beat (more like a metronome).
What are the effects of being more parasympathetic?
- Lower heart rate.
- Better recovery from workouts.
- Improved blood sugar control and resistance to fat accumulation/ease of losing fat.
- Improved digestion.
- Reduced physical performance (not as strong, fast, explosive).
- More creativity.
- Better healing.
- Adapt, assuming there has been a stimulus (see the section above).
- Less regular heartbeat (less like a metronome).
Let me sum up:
It's good to be deeply parasympathetic, most of the time. It's good to be deeply sympathetic ONLY for brief periods of time - long enough to stimulate the adaptions that make you more fit. It's bad to be sympathetic all the time.
What does this have to do with fat loss?
Fat loss is one (not the only) example of an arena where the importance of understanding the sympathetic-parasympathetic axis is important.
First, think about the things that we 'know' contribute to fat loss. Lots of exercise, stimulant consumption, caloric deprivation, fasting. These things are not really controversial on their own.
Now look at which 'way' along the sympathetic spectrum those things push us. All towards the sympathetic side of the spectrum. Now look at the effects of being chronically sympathetic.
Most of the things that contribute to fat loss also tend to push us into a sympathetic state, which itself has many effects which prevent fat loss.
Read that again. Caloric deprivation and high intensity exercise will help you create a caloric deficit and burn fat, but also contribute to pushing you into a sympathetic state where inflammation goes up, insulin regulation gets worse, and fat loss is slowed.
Is the point that fat loss is impossible? Of course not. But if you're already on the sympathetic side of the spectrum, if you're already stressed, tired, drinking too much, socializing too little, and not managing personal stress, and you ADD fasting and high intensity interval training to the mix, you MIGHT not get the fat loss results you think you will.
On the other hand, if you're young (relatively few responsibilities/stresses), healthy, with a rich social life, you're probably deep into the parasympathetic end of things. Then, if you want to get in shape, and you add Crossfit and intermittent fasting and low carb, you might end up getting great results. You might become a personal trainer, showing off your six pack abs, and whipping your forty year old clients to feel crappy about themselves for not being as successful as you are. The fact is, though, that they're probably not lazy or cheating on their diets - they might be stricter than you are. But their lives leave them less capacity to absorb stressors without tumbling into the sympathetic end of the physiological spectrum and destroying any chance they have of making progress.
Bottom line here: Sometimes more is less. If you're already stressed, you might have more success on your 'diet' by making sure you start getting more sleep and having a good laugh every day and meditating, instead of just doing more exercise and cutting out more calories.
Can we measure, with an actual number, how sympathetic we are?Yes, we can.
You probably already have a pretty good idea where you are on the spectrum. If you want something to quantify it, use your heart rate variability (HRV). This isn't the same as saying your heart rate is high or low - HRV is a measure of how much the beats of your heart vary. The more sympathetic you are, the more regular (less variation) there will be in the time between your heart beats.
You can measure HRV in a number of ways. including BioForce and the S Health app on a Samsung phone.
What's important isn't so much having a good score as learning what makes your score get better (less stressed) or worse (more stressed) and learning how to change your lifestyle accordingly. Some people get driven way sympathetic by a little alcohol consumption; others don't.
Get a BioForce and start tracking your HRV. See what kinds of things make it go up and down. If you can, make adjustments so your score gets higher. You'll be healthier and fitter for it!
What's the real take home here?There's a couple of key points lurking in this.
First, understanding where you stand on the sympathetic -parasympathetic spectrum might really help you understand why you're not recovering from workouts, getting sick, or losing weight the way you think you should be.
Second, understanding this spectrum might help you pick lifestyle changes that will help you achieve your goals but might not have seemed intuitive. When people aren't recovering from workouts, they might think to try to eat more protein or stretch more. They might not realize that going out with friends or meditating might do just as much to improve their ability to recover (by pushing them towards the parasympathetic).
Meditation just might do just as much for your physical abilities as another workout.
Aim for a parasympathetic life (punctuated by short, intense, sympathetic bursts). You'll be healthier, happier, and a better karateka.