Wellness Hub · The science of energy · 6 minute read
It's 3pm. Your focus is fading, your inbox isn't, and you reach for a lift. For most of us that's a flat white. For others it's a can from the petrol station fridge, or a scoop of pre-workout before the gym.
They all promise the same thing: energy. But feeling awake and having energy are two separate things happening in your body. One is a tiredness signal being muted. The other is fuel being made, inside your cells, every second of the day.
Once you see the difference, it changes how you think about that afternoon slump, for yourself and for the people around you.
Feeling awake
Borrowed
Source: coffee, tea, energy drinks
How: blocks the signal telling you you're tired
Feels like: a quick lift, then a dip
Fuel made: none
Being energised
Built
Source: food, turned into ATP by your cells
How: enzymes and B-vitamin helpers
Feels like: steady, all day
Fuel made: every second
01 · Awake
What your coffee is really doing
From the moment you wake up, a compound called adenosine slowly builds in your brain. The longer you're awake and the harder you work, the more collects. As it binds to its receptors, you feel sleepier. It's your body's built-in "time to rest" gauge.
Caffeine is shaped enough like adenosine to slot into those same receptors and block them. The message doesn't get through, so you feel alert. Your heart rate and adrenaline can rise too, which adds to the sense of a lift.
But nothing new has been made. The tiredness hasn't gone; it's been hidden. Adenosine keeps building in the background, and caffeine stays in your system for several hours. When it finally clears, that backlog of tiredness arrives at once. That's the crash.
Caffeine doesn't give you energy. It hides the signal that you're running low.
How much caffeine?
What's in your cup
A coffee is a moderate dose. Energy drinks and pre-workout powders work on exactly the same adenosine system, but some deliver a lot more caffeine, often alongside sugar or other stimulants.
single-dose guide for healthy adults
A café coffee is often more, depending on the shots.
Across 15 popular products tested.
Sources: FSANZ (energy drinks up to 320mg per litre; about 240mg is roughly three cups of instant coffee), EFSA via EUFIC, Griffith University.
For healthy adults, guidance is up to 200mg in one go and up to 400mg across a day. Around 100mg can affect sleep in some people when taken close to bedtime. Some pre-workout labels Griffith University tested didn't list caffeine at all, or understated it.
That's changing: in March 2026, Food Standards Australia New Zealand approved new rules capping caffeine in sports foods at 200mg a day, with businesses given two years to comply (FSANZ P1056).
"But my energy drink has B vitamins in it"
Many energy drinks list B vitamins on the can, and it's easy to assume that's where the kick comes from. It isn't. B vitamins don't act like a stimulant and you won't feel them within minutes. The rush comes from the caffeine and sugar. The B vitamins are there because they're part of how your body makes real energy, which is the next part of the story.
02 · Energised
Where real energy is made
The energy your body actually runs on is a molecule called ATP (adenosine triphosphate). Every heartbeat, muscle contraction and thought is paid for in ATP.
It's made inside your mitochondria, the tiny power plants found in almost every cell. They take the carbohydrates, fats and protein you eat and, through a chain of enzyme-driven steps, turn them into ATP.
Your body only holds a small amount of ATP at any moment, so it's constantly being used and remade. That production line never stops, and like any production line, it needs the right parts to keep running.
≈ Your body weight
of ATP made and recycled by your cells every single day
03 · The helpers
Why B vitamins matter
B vitamins don't contain energy, and they don't stimulate you the way caffeine does. They work as coenzymes: helpers that let the enzymes in your cells unlock the energy stored in food. Each one has its own job on the production line.
If any one helper runs short, the whole line slows. B vitamins are water-soluble, so your body doesn't store most of them for long and needs a steady supply. Busy schedules, hard training, stress and patchy eating can all leave you short, and low B-vitamin levels can contribute to tiredness and fatigue. No amount of caffeine fixes that.
Build energy instead of borrowing it
You don't need to give up your coffee. Enjoy it for the ritual and the lift. Just don't ask it to do a job it can't. These habits support the energy your cells actually make:
Worth sharing
A note for parents
If you have teenagers or young adults at home, there's a good chance energy drinks or pre-workouts are already part of their routine, for study, sport or the gym. The same science applies to them, with a few extra reasons to pay attention.
- Their safe limit is lower. Europe's food safety authority suggests young people stay under 3mg of caffeine per kg of body weight a day. For a 50kg teenager that's about 150mg, about what one large energy drink can hold.
- Anxiety shows up early. An expert group advising FSANZ found increased anxiety in children at around that same level.
- The label already says it. In New Zealand, energy drinks must state they aren't suitable for young children.
- Sleep is the real energy source. Teenagers need more sleep than adults, and an after-school energy drink can cut into it, setting up the next day's slump.
The best energy plan for a young person is food, water, daylight and sleep. Our Vitamin B Complex label directions are for adults, so if you're thinking about supplements for a teenager, talk to your GP or pharmacist first.
Five things to pass on
- Caffeine doesn't make energy. It hides tiredness for a few hours.
- The crash is the tiredness catching up.
- One big energy drink or pre-workout scoop can be more caffeine than a teenager should have in a whole day.
- Real energy is made in your cells, from food, and B vitamins help that happen.
- Sleep is still the best energy drink there is.
The short version
- Coffee, energy drinks and pre-workouts make you feel awake by blocking your tiredness signal. They don't create energy.
- Real energy is ATP, made non-stop by the mitochondria in your cells from the food you eat.
- B vitamins are the helpers that keep that production line running, and low levels can contribute to tiredness and fatigue.
- Young people have a lower caffeine limit, and one large energy drink can reach it.
This article is general information only and isn't a substitute for advice from a healthcare professional. Superdose Liposomal Vitamin B Complex is a dietary supplement. Always read the label and use only as directed. Supplements are supplementary to a balanced diet. Made in New Zealand from imported and local ingredients.
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