How I personify body fat. Or, why body fat is like a savings account.

You can do a lot of things with your money. You can buy Chrono Trigger. You can fix your leaky roof. You can gamble at the casino.

You can also save your money. You can put it away knowing, at some point, you might not have any income and it would be nice to have some tucked away. Maybe you plan on quitting your job or finding a new one. Or maybe you plan on retiring soon.

The safest place to put excess money is in a low interest savings account. No market crash will zap away your money overnight. It’ll just slowly accumulate.

Your body can do lots of things with its income, too. Body fat is like your body’s savings account. I wish I could make this sexier, but I can’t. What follows is my rationale as to why.

It’s probably completely wrong. Who knows. But I’m giving it a shot.

Your body gets the energy it needs from the breakdown of ATP (mentioned previously here). Think of ATP as an individual firecracker. It breaks apart, energy is released, and then you’re left with “broken” and un-useable ADP.

Luckily, the body has minions that repair ADP back into ATP, and that’s what the energy systems are all about: recycling junk to sustain energy so that you don’t keel over during whatever it is that you happen to be doing…like breathing and being alive.

Not all of these minions work by the same mechanism. These “minions” are commonly known as energy systems. You have three primary energy systems: the aerobic system, the lactic-anaerobic system, and the alactic-anaerobic system.

  • The aerobic (oxidative) system sustains output for hours.
  • The lactic-anaerobic (glycolytic) system sustains output for around 60-90 seconds.
  • The alactic-anaerobic (ATP-PC) system sustains output for around 10-15 seconds.

These systems don’t exist in vacuums. As you read this, all three of the above systems are on, it’s just that they’re only on a certain percentage based on what you’re doing with your body, and how quickly you need energy.

Imagine sprinting as fast as you can.

For the first 100M or so, you’d be alactic-anaerobic and burning through phosphocreatine stores, which regenerate energy quickly. Because PC-Minions regenerate ATP quickly, you’re at near-max energy potential with every stride.

After the 100M, you’d fade into the lactic-anaerobic energy pathway and use glycogen to replenish energy. Glyco-Minions regenerate ATP slower than PC-Minions.This is why speed drops; there’s not as much free energy floating around. You’re bursting firecrackers, but, with every passing second, less and less are being restored. And with less around, you can’t perform as well.

If you’re in terrible running shape (like me), you’ll fizzle into the aerobic energy pathway before you reach the 800M mark. You’re now at a slow jog. Or, if you’re fat like me you’re walking, and one step away from putting your hands on your knees and bowing your head. The aerobic energy pathway can use glycogen or triglycerides (stored fat) in order to replenish energy.

For lower intensity longer duration work, triglycerides get the nod because (a) they take a long time to break down and get put to use, which is fine when you don’t need lots of energy, (b) they yield a lot more energy, and (c) you have a near unlimited supply of triglycerides (collectively known as body fat), so you can maintain the low output for a long period of time.

This is how the energy systems break down in a vacuum, but life is a rabbit hole.

Multiple bouts and rest intervals mess with the time stamps on each energy system. In other words, sprinting all out for ten seconds is alactic-anaerobic. But if you sprinted for ten seconds, rested for ten seconds, and then sprinted again for ten seconds, you can bet your second sprint to push into lactic-anaerobic territory.

Protein can also sneak into the story. If you’re starving and in desperate need of energy, your body can break down protein (muscle tissue) and use it to regenerate ADP back into ATP.

Are you on the toilet right now? Because I’m starting to confuse the shit out of myself. Flush me downtown, baby.

You can ignore the complex stuff above as long as you understand most of the voluntary movement you perform in a given day is aerobic, or perhaps better said: could be taken care of aerobically.

You’re using body fat to fuel most of your daily voluntary activities.

Typing, sitting, walking, sleeping, breathing — you’re able to sustain these things for a loooonnnng period of time. Don’t get confused. Walking and jogging (and the typical McFitness exercise shtick) is also aerobic, just at a higher gradient.

Now that we’ve talked about the body, let’s talk about the brain.

Your brain is a little different than your body. Your brain likes to sip on liver glycogen (stored carbohydrates) for fuel. But liver glycogen stores are finite.

A crude estimate for liver glycogen longevity is 24 hours. So if you went without food for one day, you’d be empty. No bueno. Because no fuel for the brain makes for a dead brain.

Assuming Western eating habits, no big deal though. We eat often. And we eat the types of foods that are easily stored as liver glycogen.

But humans can survive without food for longer than one day, no matter how hangry some people get six hours after their last meal. Hangriness is a pet peeve of mine. There’s nothing worse than people crying about hunger even though they’ve eaten less than twelve hours ago.

We can survive longer than one day without food because the human body is a wizard. When liver glycogen runs out, the body breaks down its body fat to produce ketones, which the brain uses when liver glycogen runs dry.

Alright. Got all that, chief? Enough of the science crap. I probably got half of it wrong anyway. (Oops.) Now we connect two and two.

Assume zombies attack and you’re stranded in your basement. Without food. You’re like a bear hibernating for the winter.

What substance is going to keep your brain alive and kicking the longest? Fat. 

What substance is going to keep your body alive and kicking in a low intensity shut down state the longest? Fat.

Body fat is your savings account because it’s your Oh Shit fund. If you ever lose your job and have no income (aren’t eating), your savings account keeps you afloat the longest, allowing you to (attempt to) find a new job.

Humans are, shall we say, fatphillic. We have an affinity for storing body fat because our evolutionary history was filled with nutrient and energy shortages. Being fatphillic meant you could better survive those shortages. Better survival rates made for better reproductive rates, meaning those fatphillic genes were passed down over time.

Unfortunately, in today’s Western world, being fatphillic is worse for survival. Type II diabetes is on the rise, which should be renamed Pizza the Hutt Syndrome.


Because, for all intents and purposes, type II diabetes is the disease of eating yourself to death. It’s when all of your fat cells are full up with nutrients and energy, meaning the junk has no where to go. So it floats around in your body (high blood sugar) and causes mayhem.

Humans want to store body fat when possible. The “when possible” being an important qualification. Don’t read this and think you’re destined to be fat (even though if you live in the Western world, well, you kind of are).

In order to put money into savings, you have to first be taking care of your immediate expenses.

You won’t put money into savings if you can’t afford your mortgage.

You won’t get gain fat if you can’t fuel your basic survival functions.