Not having the energy is the number one explanation for not doing things, desire for energy sells us energy drinks, keeps us eating calorie dense foods, has us addicted to coffee (actually just the amount of fat and sugar you put in your coffee), etc etc.
You have all the energy you need right now, no matter what, unless you’re literally dying of starvation and are under 5 percent body fat.
There’s 9 calories per gram of fat, that’s all energy that your cells could burn to produce work.
The truth is you just don’t feel like it.
So you turn to caffeine and actually coffee perfectly captures the difference between mental and physical energy. Caffeine, as found in black coffee or tea, has no calories. It contains no energy.
A caffeine molecule is close enough to the shape of an adenosine molecule that it can fill up an adenosine receptor. Imagine a helicopter landing pad, if caffeine is on the pad then adenoise can’t land. And adenosine makes you sleepy. You feel ‘awake’ because not because you have more energy but because you’re not getting the sleepiness signal.
BTW, this causes your body to make more adenosine receptors which is where caffeine tolerance comes from.
This is also why power naps work. Adenosine makes you fall asleep but doesn’t keep you asleep, if you let yourself fall asleep you’ll clear the adenosine and wake up five minutes later slightly refreshed. Again, you don’t have any more energy – from a physics point of view – you’re just experiencing the absence of sleepiness, a mere mental state.
Another thing that has no calories that blocks adenosine is light. Full spectrum light like my veralux happy light I turn on every morning in the dark Canadian winter.
If you can’t get some sunlight, get some fake sunlight and you’ll feel more energetic. Taking vitamin D (with appropriate amounts of calcium and vitamin K) helps as well.
So let’s talk about the other drug people use to try and have more energy that does contain calories: Sugar.
Now sugar does contain energy and it glucose is vital to the brain. If you have no glucose your brain can run on ketones but your body loves glucose so much it can use the liver to even turn protein in sugar. Neat.
If you ingest sugar while you’re doing something your body will grab it right up. In fact, carbohydrates just entering the mouth causes cyclists in an experiment to produce more power.
Aside from that I’m just going to link to this article about sugar. It’s really good.
The thing is if you’re not moving your body just stores that sugar for later, as fat. Energy isn’t use it or lose it, all that you accumulate you store.
Adding more energy to your system won’t get you moving, won’t make you feel like moving. Mental and emotional energy doesn’t track with physical energy. I’m at my most excited after a 10k run or a squash game because the oven is hot, burning lots of fuel lets your body know there’s lots of fuel to burn.
The final way that mental and physical energy is different is actually a way that they are very much the same, they both run on glucose for fuel. Your brain actually uses most of the glucose you consume. And yes, you can be exhausted by thinking, being emotional drained is physically draining – all those thoughts and feelings you have are coming from the same neurotransmitters that respond to physical threats.
With one difference. Your muscles store energy in the form of glycogen. No matter how exhausted you are from math or dealing with people or whatever you do have the physical energy to exercise or run from a lion or go dancing.
And you don’t even need to top your brain up with glucose, honestly. As mentioned before, your body will produce ketones to keep your brain running. This is why people in ketosis aren’t zombies (although, oddly, people loaded on sugar are, but I’m not going to get into carb-related brain fog in this post). Anyone who has ever fasted knows there’s a weird and often sudden mental clarity that kicks in. That’s ketones. And that’s proof positive that mental and physical energy are completely different.
To wrap up I’m not saying that I don’t feel like it is always an invalid excuse, sometimes your body is telling you to back off training using emotional signals that you shouldn’t override.
But just to be sure, just to Leave No Doubt, why don’t you get started and see. Most of the time the heaviest lift at the gym is front door. Procrastination, fear, comfort, these are the much more likely culprits than a lack of energy.