Why artificial intelligence may trigger an obesity epidemic of the mind
At some point in the not-too-distant future, the idea of a brain gym will stop sounding whimsical and start sounding inevitable.
Not a meditation app. Not a productivity hack. An actual, deliberate system designed to make thinking harder than it needs to be.
Which sounds absurd until you remember that this is already how we treat the body.
We lift heavy objects for no practical reason. We run nowhere, repeatedly. We pay good money to sweat indoors.
Not because it’s natural. But because the modern world quietly removed effort — and our biology didn’t cope well with the upgrade.
The argument here is simple, if slightly unsettling:
Artificial intelligence may do to human cognition what ultra-processed food did to human metabolism.
And if that’s true, we may be heading toward an obesity epidemic of the mind.
Why effortful thinking mattered in the first place
To understand why this matters, we need to revisit a distinction most behavioural scientists carry around like a favourite old coat.
In Thinking, Fast and Slow, Daniel Kahneman described two modes of thinking:
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System 1 — fast, intuitive, automatic, effortless
System 2 — slow, deliberate, analytical, effortful
System 1 is cheap. System 2 is expensive.
And crucially, the brain strongly prefers the former.
System 2 thinking burns energy, demands attention, and feels like work. We only engage it when the environment forces us to — when problems are unfamiliar, stakes are high, or mistakes are costly.
For most of human history, the world reliably triggered System 2:
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survival decisions mattered
errors were punished
complexity couldn’t be bypassed
Effortful thinking wasn’t optional. It was unavoidable.
Artificial intelligence changes that bargain.
What AI actually removes (and why the brain loves it)
AI doesn’t just make thinking faster. It absorbs the System 2 load.
Drafting, structuring, summarising, synthesising — the cognitively demanding steps that once forced slow, effortful reasoning can now be delegated instantly.
From the brain’s point of view, this is not concerning. It’s a gift.
Why burn glucose engaging System 2 when a fluent answer arrives fully formed?
The brain doesn’t ask:
“Will this reduce my long-term cognitive resilience?”
It asks:
“Can I get away with this more cheaply?”
And increasingly, the answer is yes.
The brain: miraculous, expensive, and relentlessly economical
The human brain is a marvel. It is also a metabolic liability.
It makes up about 2% of our body weight and consumes roughly 20% of our resting energy. From an evolutionary perspective, this is extravagance bordering on irresponsibility.
There is a serious argument — most famously made in Geoffrey Miller’s The Mating Mind — that the brain itself may be a sexually selected trait. Like the peacock’s tail, it is costly, inefficient, and difficult to maintain — yet persists because it signals surplus capacity. (On a massive tangent - I subscribe to Robin Dunbar's social brain theory instead).
But once that organ existed, natural selection immediately went to work optimising how often it had to be used.
System 1 became the default. System 2 became something we reluctantly switched on. Effort became something to avoid unless necessary.
Which worked beautifully — until effort stopped being necessary at all.
Food broke the body. Abundance did the damage.
The obesity epidemic didn’t happen because humans suddenly lost willpower.
It happened because biology met abundance.
We evolved in an environment where energy was scarce. Craving fat and sugar was adaptive. Resting when possible was sensible. Saving effort was survival.
Then we built a world of:
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cheap calories
constant availability
engineered deliciousness
And our bodies did exactly what they were designed to do.
In the US today, around 60% of adults are obese. Not because people stopped caring, but because the environment removed constraint.
Our response wasn’t moral outrage.
We built gyms.
We reintroduced effort deliberately.
AI is cognitive abundance
Artificial intelligence is the same story — this time for thinking.
It makes:
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System 2 optional
effort avoidable
shortcuts irresistible
The danger isn’t occasional use. Doughnuts are fine. Calculators are fine. AI is fine.
The danger is default reliance.
When effort disappears:
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adaptation slows
capacity atrophies
resilience erodes quietly
And we’re already seeing the early signs.
Educators report students arriving at university less comfortable with sustained thinking, and increasingly willing to outsource it — not out of laziness, but efficiency.
Why struggle when the answer is instant?
System 1 nods approvingly. System 2 stays switched off.
Social media was the warm-up
We’ve already seen what happens when cognitive environments reward speed, certainty, and emotional salience.
Shorter attention spans. Lower tolerance for ambiguity. Reduced patience for slow thought.
Generative AI doesn’t create a new problem. It accelerates one we already live with.
Cognitive reserve: why training matters later
There’s a robust finding in neuroscience that people with higher education and lifelong cognitive engagement tend to experience later onset of dementia and Alzheimer’s symptoms.
Not because they avoid pathology.
The plaques still form. The disease still progresses.
But their brains cope better.
This is explained by cognitive reserve — the brain’s ability to reroute, compensate, and do more with less as systems degrade.
And cognitive reserve is built the same way muscle is: through load.
Effortful thinking matters not just now, but decades later.
Remove it, and we may be quietly eroding resilience we’ll desperately want to have.
Which brings us back to brain gyms
Brain gyms aren’t a gimmick.
They’re a response to abundance.
Just as physical health now requires:
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deliberate resistance
artificial strain
chosen difficulty
Cognitive health may soon require:
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environments that force System 2
tools that resist automation
norms that reward effort, not just fluency
Not because struggle is virtuous. But because adaptation requires load.
The quiet danger of “better, quicker thinking”
AI won’t make us stupid.
It may make us cognitively unfit.
The obesity epidemic didn’t happen because food became evil. It happened because effort disappeared.
The cognitive version will be no different.
Unless we recognise it early — and design for resistance, not convenience.
Brain gyms won’t be nostalgic. They won’t be anti-technology. They’ll be the cognitive equivalent of lifting heavy things in a world that no longer requires it.
And in an age where thinking has become effortless, that may be the most important effort of all.