Jen Oliver: Welcome to the, so that's Why podcast where we unpack the
science behind everyday questions.
I'm Jen.
Chris Smith: I'm Chris.
Matt Edmundson: And I'm Matt.
Jen Oliver: Right.
So today's question.
Why do we get food cravings?
You know, that moment when you, you sat there minding your own
business and suddenly your brain is absolutely convinced that
nothing in the world matters except getting your hands on chocolate or
crisps or both at the same time?
Matt Edmundson: Yeah, for me it's both.
Uh, I can be completely full from dinner and then two hours later
I'm standing in front of the fridge and it'll be 10 o'clock at night.
And I'm having a sort of staring contest with a slice of cake, genuinely sort of
negotiating with myself about whether just a slice really means just one slice.
Jen Oliver: No, it never does.
Chris Smith: I dunno what you mean, Matt.
What you talking about?
Jen Oliver: Of course you don't.
But what's fascinating is that cravings are completely different from hunger.
Hunger's your body saying, I need energy.
It's open-minded about what you eat.
Cravings.
Are your brain demanding something incredibly specific, like it's
placed an order at a restaurant and it won't accept substitutes.
Chris Smith: So here's a stat that probably won't surprise you.
Um, research shows up to 97% of people experience food cravings
at some point in their lives.
So pretty much everyone, uh, so we're talking about something
that is essentially universal.
Matt Edmundson: 97%.
I think the other 3% are actually.
Lying.
Yeah.
Uh, and so I'm guessing by the end of this guys, I'm gonna have a scientific excuse
for my 10 o'clock cake habit, right?
Chris Smith: Well, maybe a loose one.
Matt Edmundson: Okay.
Chris Smith: Uh, so we'll explore, I
Matt Edmundson: say wherever I can go.
Yeah.
Chris Smith: Well explore why cravings mean your brain is doing
exactly what it's designed to do.
Just in envir an environment full of tempting snacks and treats
it wasn't designed to cope with.
We'll cover why chocolate is top of the pops when it comes to cravings and
discuss whether cravings do actually signal nutritional deficiencies.
Jen Oliver: So here's something I find remarkable.
When you experience a craving, your body actually undergoes
measurable physical changes.
You know, increased elevation, elevated heart rate, heightened stomach activity.
Your entire system starts prepping for food before you've
consciously decided anything.
Matt Edmundson: So, lemme get it straight, right?
My body has committed.
To the biscuit, Tim, before my brain has even finished
weighing up the pros and cons.
Dunno about you.
That feels like a little bit of a conspiracy to me.
Chris Smith: Well, it kind of, because your physiology is very persuasive.
Um, and the foods we crave follow a clear and very naughty pattern.
They're almost always sugary or salty or fatty, or combinations of all three.
These foods hit reward regions in the brain in ways that
simpler foods just don't.
Jen Oliver: Which is probably why no one's ever messaged their partner saying,
pick up some celery on the way home.
'Cause I can't stop thinking about it.
Matt Edmundson: I'd be worried if they did, Jen.
Not gonna lie.
I'd be really worried.
Jen Oliver: Okay, so here's where it gets interesting.
A lot of this comes down to the brain's reward system.
Specifically a pathway called the Meso Limbic dopaminergic pathway.
Matt Edmundson: Congratulations.
That's a bit of a mouthful.
Jen Oliver: Yeah.
You say it quickly with confidence
and this system, it uses dopamine to signal motivation and reward.
Chris Smith: It does, and it connects to areas of the brain, like the nucleus
accumbens, which helps process pleasure.
And the prefrontal cortex, which is involved in decision
making and self-control.
Together, these regions influence what feels rewarding, what grabs attention, and
which behaviors we're likely to repeat.
Matt Edmundson: Very good.
So Jen, you mentioned dopamine.
Isn't that the happiness chemical?
Jen Oliver: Well, that's the common perception, but it's a bit more nuanced.
Dopamine is actually more about wanting and anticipation than pleasure itself.
When food predictive cues show up like the site of a bakery, the smell of pizza,
even just thinking about your favorite foods, it's probably happening to you now.
Dopamine surge is creating that subjective feeling of craving.
Matt Edmundson: It is definitely happening to me now.
Uh, there's no doubt.
So this explains them why I can walk past, say, a chip shop.
Um, without being hungry, but calf catch that sort of whiff of vinegar.
Sorry for anybody outside of the uk, but um, and suddenly
I'm convinced I'm starving.
Right.
My brain has essentially been hacked by the smell.
Yeah.
Chris Smith: And that is a perfect example of conditioning.
So research shows that even previously neutral stimuli can trigger cravings
after being paired with food consumption.
In one study, participants who were exposed to serving trays
paired with chocolate, subsequently experienced cravings when
just showing the trays alone.
No chocolate present.
Just the tray was enough.
Jen Oliver: I'd feel robbed.
But if you always snack when you're watching television, I guess simply 10 and
on the TV can trigger cravings regardless of whether you're actually hungry.
And time of day works the same way.
If you always have something sweet at 3:00 PM at 3:00 PM
your brain starts expecting it.
Chris Smith: And the food industry understands this extremely
well, so-called hyper palatable.
Foods like chocolates and snacks are specifically
engineered to maximize reward.
And of course, advertising creates associations between their products
and these positive emotions.
Matt Edmundson: So they're basically creating the Pavlov's
dog experiment, aren't they?
Except for.
We're the dogs, and the bell is every advertisement, every smell,
and every moment of the day.
Jen Oliver: Yeah, you're right.
And I think also a lot of people struggle to tell the difference
between physical hunger and emotional cravings in the moment.
Um, because physical hunger develops gradually, it's regulated by hormones
like ghrelin signaling hunger and leptin signaling fullness.
And you feel it in your stomach, and it can be satisfied by eating
until you're comfortably full.
Chris Smith: That's it.
And emotional cravings are different.
So they come on suddenly and intensely, and they're often alongside
stress, emotions like, um, sadness or boredom, or even happiness.
So rather than stomach sensations, they're experienced as what researchers
call head hunger, like a mental preoccupation with specific foods.
And interestingly, or worryingly, they persist even after eating to fullness.
Jen Oliver: Mm.
Matt Edmundson: Which is crazy.
So we eat because we feel bad, then we feel bad because we've eaten and then
we eat because we feel bad about eating.
And you, the loop continues.
Jen Oliver: Exactly.
And that guilt perpetuates the cycle because negative emotions
themselves can become triggers.
Matt Edmundson: Okay.
So what actually then kicks off the cravings?
What are the main triggers?
Chris Smith: So chronic stress is huge.
So when you experience prolonged stress, your body releases elevated
levels of cortisol and cortisol directly stimulates appetite and
increases cravings, particularly depressingly for calorie dense foods.
It actually alters the reward response, making comfort foods feel
more preservable and temporarily reducing stress related emotions.
Matt Edmundson: So when people say then that they're stress eating,
that's not just a figure of speech.
Chris Smith: No, not at all.
And sleep deprivation has a similar effect.
So even a single night of poor sleep disrupts your appetite hormones.
Ghrelin goes up, leptin goes down, and brain imaging shows that.
Sleep loss impairs your prefrontal cortex while amplifying
emotional processing regions.
One study found that sleep deprived participants were up
to 55% more likely to be obese.
Matt Edmundson: That's insane.
Jen Oliver: Yeah.
Matt Edmundson: So my, my very terrible decision then to stay, uh, up
watching, you know, one more episode of whatever series is on at the moment
is directly linked then to my terrible decision to demolish half a packet
of digestive biscuits the next day.
Jen Oliver: Yeah, but that depends what you are watching.
Matt Edmundson: That's so true.
Jen Oliver: And hormonal fluctuations also play a role, particularly
during the menstrual cycle.
The hormonal changes can cause blood sugar levels to drop, promoting your brain
to signal for sugar, and your serotonin levels also drop and eating carbohydrates
temporarily boosts those levels, and so that gives a bit of a mood relief.
Matt Edmundson: Okay, so what about dietary jurisdiction then?
'cause I've heard that trying to avoid certain foods can make the cravings worse.
Is that right?
Chris Smith: Absolutely.
It's well established.
So when people label foods themselves as forbidden or they
actively try to suppress thoughts about them, that cravings increase.
It's called ironic process theory.
So deliberately trying not to think about chocolate cake makes
it more mentally accessible.
Okay.
Jen Oliver: And studies confirm that participants on restrictive
diets report more food cravings, and those on like really low calorie
diets are more likely to overeat previously banned foods when they stop.
Matt Edmundson: Okay, that's good.
So I, I can now feel vindicated for never having these successful
completed a diet in my life.
Jen Oliver: So now here's the big one.
I wanna tackle the idea that craving signal nutritional deficiencies.
Chris Smith: Well, sorry to do my usual myth busting thing, but
the concept is largely debunked.
So like the idea that craving chocolate means you need more magnesium.
Let's be honest.
If cravings truly reflected nutrient needs, we'd expect people
to crave nutrient dense foods like spinach or nuts when deficient.
Instead, cravings overwhelmingly target these hyper palatable,
very tasty processed foods.
Jen Oliver: And the chocolate magnesium connection's actually
been tested, hasn't it?
So when chocolate CRAs consumed white chocolate.
Which contained no magnesium, their cravings were reduced just as
effectively as with dark chocolate.
It's the fat and sugar content drive in the craving, not magnesium,
Matt Edmundson: which is a real shame.
So my chocolate craving then isn't my body's uh, sort of sophisticated
way of requesting yet more minerals.
Yeah, I dunno what to say about that really.
Let's move on.
Chris Smith: I bet, I bet.
Still enjoyed the study though.
I'm sure it's
good.
Jen Oliver: But there's another angle to this that I find genuinely wild.
Matt Edmundson: You need to get out more of.
Jen Oliver: I really do.
Matt Edmundson: Genuinely wild.
You definitely need to get out more.
Sorry.
Jen Oliver: It's wild.
It's the gut microbiome.
So your gut bacteria communicate with your brain through what's
called the gut brain axis.
Different bacterial species thrive on different nutrients.
So some reacher researchers suggest that microbes might actually
influence the cravings to get the foods they need to grow.
Wild, wild.
Alia.
Matt Edmundson: Wild.
This is so wild.
So what you're telling me then, let me get the wildness correct.
Is that the bacteria in my gut are manipulating, which is such a good
word, they're manipulating me, uh, into eating what they want.
Jen Oliver: Yeah, I mean, it sounds farfetched, but
the research is compelling.
So individuals who are chocolate desiring have different microbial
metabolites compared to chocolate in different individuals.
Even when eating identical diets and that suggestion, microbiome composition
is influencing your preferences.
I need to get on these chocolate studies.
Never invited on them.
Chris Smith: Yeah.
Should we just do one anyway?
Yeah,
Jen Oliver: yeah.
Invite to a
Chris Smith: chocolate study.
Matt Edmundson: I'll take one for the team's.
No problem.
Chris Smith: And to go further here, so ESA study even identified the
specific or a specific bacterium, and it's called Bacter Vulgarus, and that
is casually linked to sugar intake.
And it works through gut receptors that affect hormone secretion
and ultimately brain circuits controlling dietary choices.
So yeah, it's kind of telling us what to eat, what he wants us to eat.
Matt Edmundson: So there's an entire ecosystem in my gut with opinions
about what I should eat for dinner.
That's just brilliant.
It's a great excuse, isn't
Jen Oliver: it?
The exciting thing is, sorry.
Even more wild, is that 'cause our microbiome can be influenced by what
we eat, prebiotics and probiotics.
There's a potential for targeting gut health as a way to manage cravings.
It's still emerging research, but the connections real.
Matt Edmundson: Okay, so, uh, wildness aside then, what can people actually,
what can I do about this more importantly?
Jen Oliver: Okay.
So mindful eating has emerged as a powerful approach, and that involves
distinguishing true physical hunger from emotional urges, being present during
your meals, noticing your triggers.
Studies show that viewing cravings as temporary mental events rather
than commands you must obey.
They consistently reduce intensity of cravings.
Chris Smith: Yep, absolutely correct.
And there was a six week study performed that found that mindful
eating, reduced binge eating episodes from four to one and a half per week.
So this approach works through awareness, not willpower or restriction.
Matt Edmundson: Okay, so instead of thinking I must have chocolate
right now, it's, I'm experiencing a thought about wanting chocolate.
And I love that phrase, Jen, that you said.
What was it?
I'm having a temporary mental event.
I'm gonna, this Is
Jen Oliver: your family gonna love
this?
Matt Edmundson: Yeah, it's gonna follow me around the whole of my life.
Now, masters having another temporary mental event.
Everybody, TME.
Jen Oliver: Exactly, but you observe the craving.
You acknowledge it's there, but recognize you don't have to act on it.
It takes practice, but genuinely works apparently.
Chris Smith: That's it.
And another thing to do.
So when, when a craving does strike, simple strategies help.
So distance yourself from that trigger, as hard as that might be.
Even set yourself a timer for 20 to 30 minutes and just do something else.
Because many cravings pass on their own.
They're not permanent states, and a big one is drinking water.
So if you drink a glass of water, when you've get getting a craving,
it can help too, because a lot of thirst signals are mistaken hunger.
Matt Edmundson: Okay, I'll try the drinking water thing, but
what about people who have tried.
All of that and still find themselves raid in the cupboards.
Chris Smith: So as crazy as this might sound, taking back the control helps.
So giving yourself permission to occasionally enjoy crave foods mindfully
without guilt, can reduce their power.
Matt Edmundson: Have got the power.
Yeah.
I
Chris Smith: really dunno what to say about that.
Um, so total restriction.
So taking away.
Craving well crave foods, completely intensifies cravings as we discussed.
So the goal isn't perfection, it's understanding what's happening and
making conscious choices rather than feeling controlled by these urges.
Matt Edmundson: Brilliant.
Okay guys.
So why do we get food cravings?
Chris Smith: So food cravings are driven by your brain's reward system.
Dopamine signaling creates intense motivation to seek specific foods that
trigger by conditioning, by stress.
Poor sleep.
Hormonal fluctuations and environmental cues
Jen Oliver: and not by nutritional deficiencies.
Despite what you might have heard, your body isn't sending your
use sophisticated signals to eat chocolate 'cause you need magnesium.
It's your reward circuits responding to a lifetime of positive food experiences.
Amplified by whatever's going on in your life and your body at that moment.
Matt Edmundson: So when I'm convinced I desperately need chocolate 11:00 PM it's
my brain's conditioning combined with whatever stress I've accumulated that day.
Not some mineral deficiency I should be listening to.
Jen Oliver: Exactly.
And understanding that is genuinely useful.
Once you know cravings are driven by conditioning and circumstance rather than
nutritional wisdom, you can work with them rather than feeling controlled by them.
Chris Smith: So that's why we get food cravings.
Your brain is doing exactly what it's designed to do.
Just operate in, in a modern environment full of hyper palatable
foods and constant food cues that I biology just wasn't built for.
Jen Oliver: So that's it for this week.
Make sure you hit that subscribe button.
We're unpacking the science behind everyday questions each week.
Tell us in the comments what you'd like us to explore.
Thanks for geeking out with us, but for now, that's it from me.
Matt Edmundson: That's it from me,
Chris Smith: and that's it from me.
Jen Oliver: Bye for now.