Name: What Actually Happens When You Are Sick?
Uploaded: 2026-01-24T17:19:48.000Z
Duration: 11 min 12 s
Description: VoiceTubeの動画で発音を聞きながら英語表現を覚えよう！学べる英語：

There's this idea floating around that what doesn't kill you makes you stronger, that surviving a disease leaves you better off.

転換語

And it seems to make sense because we've all experienced this.

When you go through hardship, often you come out more resilient, more ready to face a difficult situation in the future.

But it turns out that sometimes what doesn't kill you makes you weaker.

The machinery of war Think of yourself as a large country with a sizable army to defend it.

You're surrounded by enemies that want to take your land, your energy, your resources.

So your body evolved to be sensitive to damage and to the presence of enemies.

Because this means that an invasion might happen at any moment and that it has to act fast.

Let's start an invasion and see what happens.

The moment your cells notice that something is off, they release an onslaught of signal proteins called cytokines.

They're like air raid sirens that activate all sorts of immune cells that then themselves release many more cytokines, amplifying the alarm.

Soon you're flooded with signals that trigger precautions and countermeasures.

Mobilization is your brain activates sickness behavior and reorganizes your body's priorities to defense.

The first thing you notice is that your energy level drops and you get sleepy.

You feel apathetic, often anxious or down, and you lose your appetite.

Your sensitivity to pain is heightened and you seek out rest.

All of this serves to save your energy and reroute it into your immune response.

You become a country under attack, switching into a war economy.

Because properly activating your immune system is intensely disruptive and dreadful.

Just like war is expensive for a country.

As industry switches to building tanks, your immune system demands huge amounts of energy.

Amino acids and micro elements to build its weapons.

It speeds up your metabolism and makes your cells work harder and faster while creating heat.

That's pretty stressful for many invaders, but it uses up a lot of calories to maintain.

Then your immune system begins to clone millions of specialized immune cells to respond specifically to the enemy infecting you.

B cells produce million of antibodies every second, each requiring hundreds of amino acids to construct.

Billions or even trillions of proteins need to be made to refresh the complement system.

The mobilization and information signals also need constant refreshing.

Usually, you acquire your resources by eating.

But when you're sick, your body slows down your digestion because it needs a lot of energy you can't spare, so it reaches for the easiest source of amino acids and starts breaking down your muscles.

All that muscle that you worked so hard for is sacrificed to keep you alive.

If you're young and healthy and fit, you'll make up for that quickly once you're better.

But if you're old or very young, weak, or suffer from chronic illness, this may be way too draining.

Your body is literally consuming itself to keep the defense going.

If your whole system is already strained when you get sick, Just keeping your immune responses going can overwhelm your capacities.

Your immune system is as dangerous to you as it is to enemies.

There's a very fragile balance between the damage caused by an infection and the collateral damage caused by immune cells.

One of your first responders are neutrophils.

Imagine crazy, aggressive chimps with machine guns.

If a neutrophil encounters enemies, it showers them with chemicals that cut them open, but

can also damage civilian cells, Especially if the patient is already compromised, for example, by smoking.

On top of that, the microorganisms that invade you Often release chemicals and toxins that can cause significant damage and cell death.

So a serious infection often causes many tiny wounds, literally holes in your organs.

As you can imagine, it's not great to have holes and wounds in your organs, and

Your neutrophils and macrophages help by releasing chemicals that signal the body to start repairs.

And most of the damage is quickly filled up with regrowing cells.

But others are filled with collagen, A sort of fix all organic cement that gives your gooey tissue structural integrity.

You've seen the result on your skin as scars.

A scar is different from the original tissue.

It's like a sloppily applied cement patch.

It can't do what the original tissue was doing.

A scar on your heart makes it tiny bit weaker.

A scar on the lungs no longer captures oxygen.

A scar on your liver makes it a worse filter.

And so, as you go through life and survive serious disease after serious disease, the functionality of your organs may decrease.

The damage is usually small enough not to affect your quality of life, but can be permanent.

there is actually something you can do to avoid a lot of this damage and train your immune system.

The best way to train your immune system, Your immune system is unique.

Everyone has a slightly different immune system that's stronger against some enemies and weaker against others, which makes evolutionary sense as this protects our species from being wiped out By a single infection.

Collectively, the immune system of the human species is a spectrum.

Most people respond well enough to an infection.

A few are super responders, and a few don't respond well and die.

Some people survived the Black Death, are more resistant to HIV or coronavirus, or even resistant against Ebola.

Others are killed easily by the flu or are highly vulnerable to certain bacterial infections.

Where you are on this spectrum is impossible to predict.

And you also respond differently to every possible infection.

This is why seemingly very healthy young people died from COVID while for some elderly people, it was more like a mild flu.

The idea that you can weather all sorts of diseases if you never get a cold is wrong.

You never know what your immune system is good at until it's tested.

Getting sick is a gamble in life's casino, with your health on the line always.

Hacking one of the best features of your immune system.

When you survive a disease, usually you have better defenses against it.

Afterwards, you gain memory cells that are very good at killing the specific enemy you fought that day.

So you either don't get the disease again, or the next infection is much milder.

And you can use an incredible achievement of human ingenuity that taps into this mechanism to prevent damage from disease and train your immune system.

Vaccines basically pretend to be a disease and train your defenses to be ready if it ever shows up for real.

The goal is to create the same memory cells that you would get after surviving an infection.

But if you can feel some side effects, why should you still do it?

You have two options to train your immune system.

In vaccine dojo, you train with paper weapons and learn to defend yourself.

Sure, you might get a black eye or a bruise.

Sometimes after a vaccine, you get sick for a few days, but that's generally it.

We discussed vaccine side effects in detail in another video if you want to learn more.

On the other hand, getting a disease to become immune means going to a nature dojo.

In nature dojo, you train with real weapons, sharp knives and swords.

Things might still work out, but with way more cuts and wounds.