- I'm often asked if it's okay to eat fruit
when trying to lose weight?
And I think the reason is this.
We know that sugar is bad for us,
and causes weight gain, and fruits contain sugar,
so surely fruit must be bad for weight loss?
Or is it that because the sugar in fruit is natural,
does that mean its okay?
Because after all, we're told we should eat fruit
because there is loads of good stuff in there
like vitamin C, flavonoids, and fiber.
Does do these good things somehow balance out
the sugar and make eating fruit okay?
Let's find out.
(intro music)
Hey, Carb Dodgers. I'm Doctor Dan Maggs.
I'm so glad you've landed on my channel,
which is all about achieving lasting weight loss
through low carb, real food nutrition.
If that's something that is of interest to you,
then make sure you've subscribed to my channel
so that you get notified whenever I upload a new video.
Let's start with the sugar thing.
The word sugar can be used for a few things,
so I just want to clear this up.
Typically, when we think about sugar,
we think about table sugar or sucrose.
Sucrose is a two part molecule
made up of glucose and fructose.
Yet when people think about the sugar in fruit,
we often think of it as just fructose,
which is frequently called the fruit sugar.
And yes, fructose is the main sugar in most fruits,
but they also contains glucose.
Sometimes people call glucose the blood sugar
because it's the main sugar in our blood.
We also find sucrose in fruits too,
but the body quickly digests that
and we're just left with glucose and fructose.
So yes, these sugars come from fruit,
which we can say is natural,
but the body does not know if that glucose or fructose
came from a banana or a chocolate bar.
By the same logic, table sugar also comes from plants,
sugar cane or sugar beet, so could be considered natural.
I think it's more helpful to think of them
as naturally occurring sugars versus added sugars.
That is, sugar that naturally occurs in whole food
versus sugar that we add in to food.
And it's important to note that these added sugars
are the overwhelming source of sugar in our modern diets.
There's one place that fructose can appear
in quite high concentrations in nature too,
and that is in honey.
Now, bears love honey and use it to gain weight
before they hibernate.
Some of you will be familiar with Winnie-the-Pooh.
If you are, you'll recall that his favorite food was honey,
and that he was also rather fat.
Which, as it turns out, was no coincidence.
So let's find out what is it about fructose
that makes makes bears and humans gain weight.
For us humans, being overweight or obese
is not important for survival in the modern world,
but for our ancestors, it was critical.
Nature wants us to survive when times are rough,
for example, surviving a harsh winter.
Being able to effectively store fat during summer and autumn
would have been a great advantage to our ancestors.
Anyone who had a genetic advantage that meant
that they were good at making and storing fat
stood a better chance of surviving.
This in turn meant they were more likely to reproduce
and pass those genes on to future generations.
The modern human's ability to gain fat so effectively
is a direct result of this strong evolutionary pressure.
Let's think about fruit in the wild.
As fruits get riper, they get sweeter,
and many animals will gorge on fruits
in the late summer and autumn to fatten up
ready for the winter where food might be scarce.
Fruits evolved to attract animals who like the sweet taste.
Animals eat the fruits and spread the seeds
and so ensure new plants grow.
In turn, the plants give the animals the energy they need
to survive the harsh winter that follows.
It's an example of a symbiotic relationship
that has served both plants and animals for millennia.
We see this weigh gain elsewhere in nature too.
Migratory birds also switch from an insect-based diet
to a fruit-based diet to fatten up
in order to provide themselves
with the necessary energy for their long flights.
And we now know that fructose
is the major driver of this weight gain.
The glucose from the fruit can be utilized
by most cells in the body for energy.
If it's not immediately needed, it will be stored for later
either as glycogen or as fat.
But in this video, I want to focus mainly on fructose
because fructose is metabolized in a very different way.
Fructose metabolism is unique
in that it occurs primarily in the liver
where it's turned mainly into fat.
Some of that fat will get transported
out and around the body and stored under our skin as fat,
but lots of it will get stored around our abdominal organs
in what is known as visceral fat.
I'm sure you don't need me to tell you
that the fat stored around our middles
is dangerous for our health.
If you add even more fructose to the liver,
some of that fat will end up getting trapped in the liver
leading to the development of fatty liver disease.
We know that somewhere between 50 and 90% of people
with obesity also have fatty liver disease.
Fatty liver disease causes insulin resistance
and eventually type 2 diabetes.
Fructose consumption also slows our metabolism down.
Fructose doesn't just simply cause us to put on fat,
our metabolisms slow down too, think hibernating animals,
so we don't burn fat as readily.
We know that people who are overweight or obese
burn less fat.
And fructose also causes leptin resistance.
Leptin is a hormone that is produced by our fat cells.
Under normal circumstances,
it tells our brain that we're full
and that we should stop eating.
But fructose causes leptin resistance,
and the normal feedback system
that tells us to stop eating is less effective.
We're hungrier, so we eat more and we gain more weight.
Fructose also stimulates hunger in other ways too.
The effects of leptin resistance are further compounded
by the fact that fructose metabolism
causes a low energy state within our cells
that mimics starvation.
Our bodies see this as a crisis,
therefore triggering hunger to try and correct this.
If we continue to consume fructose-rich foods,
this will just continue.
It's a vicious cycle or a positive feedback loop.
So yes, fructose causes you to store fat,
slow your metabolism, and it makes you more hungry.
And this all makes sense
when we think about it from a survival perspective.
All of those things are good,
even type 2 diabetes makes sense
from an evolutionary point of view.
Higher blood glucose levels
means brain function is protected even when food is scarce.
We're genetically hardwired to gain weight
when we consume fructose.
But that same system that was so important for our survival
now predisposes us to develop obesity
when our diet is high in fructose.
It also underpins the vast majority of metabolic diseases
that we see so prevalently in the world today.
So how much fructose is bad?
Until now, I've sort of presented this like a switch.
Fructose consumption triggers all of this,
but as Dr. Richard J. Johnson says
in his book "Nature Wants Us To Be Fat,"
it is better to think of it like a dial
where as you turn that dial up and consume more fructose,
the more negative the effects become.
As with all toxins, the dose is critical.
Fructose isn't toxic to the body at low doses.
The problems start when fructose
rapidly accumulates in the liver at high concentrations.
The slower fructose is delivered to the liver,
the less toxic the effects.
The small intestines also act as a fructose shield.
I mentioned earlier that the liver is the place
where fructose is mainly metabolized,
but it's not the only place.
A small amount of fructose gets converted into glucose
by the small intestines soon after it's been consumed,
so it never even gets to the liver.
We can therefore consider the small intestine as a shield
that protects the liver from fructose.
So all of us,
irrespective of our weight or metabolic health,
can consume small amounts of fructose
without it ever getting to the liver.
However, higher doses of fructose, above about 5 grams,
overwhelm this shielding capacity.
So is eating fruit going to provide enough fructose
to trigger the negative effects?
Well, not all fruit is created equal.
Different fruits contain different amount of fructose.
Some are low in fructose and some very high in fructose.
The National Healthy Eating Guidelines here in the UK
suggest that we should eat at least
five portions of fruit and vegetables a day.
If we therefore chose higher fructose fruits
such pears, mangoes, or watermelons,
it's possible to be consuming
in excess of 75 grams of fructose a day.
And remember, that's a minimum recommendation
of five fruit and vegetables a day, not a maximum.
Now, this level of fruit consumption is nothing
compared to the amount of fruit that bears gorge on
prior to their winter hibernation
where a single bear
can eat many thousands of berries daily.
But for those of us who are trying to lose weight
and who may have underlying metabolic issues,
such as fatty liver disease,
and as I already mentioned, most do,
then clearly consuming this amount of fructose
under the illusion that it's actually healthy
is clearly a bad thing.
And fruits are also getting sweeter.
Us modern humans have been fiddling around
with fruit and vegetables to make them more marketable,
and that usually means making them
sweeter and less fibrous.
The fruit we consume today hasn't always been this sweet.
It's been bred and modified to be larger and sweeter
compared to the fruit
even our grandparents would have eaten.
Fructose is sweeter than glucose,
so in order to make fruits and vegetables sweeter,
we're increasing the amount of fructose.
The same is true for vegetables too.
Have a look next time you go shopping.
You'll often see carrots described as sweet.
Should carrots really be sweet?
And my personal favorite, supersweet sweetcorn,
as if it wasn't sweet enough already.
What about dried fruit?
Drying fruit significantly increases
the concentration of fructose.
The fructose concentration of grapes, for example,
is massively increased by drying them out
and turning them into raisins.
Add to that that most nutrients are destroyed
by the drying process,
makes dried fruits just an effective sugar delivery system.
The same goes for those dried fruit rolls aimed at kids.
Yes, it might be better
than spooning sugar into their mouths, but not by much.
Eating fructose is better than drinking fructose
because fiber is protective.
Many fruits, as well as vegetables,
are also rich in soluble fiber,
which can slow the absorption of fructose.
So yes, the fiber in whole fruit
will slow down the digestive process
and lead to fructose being delivered
more slowly to the liver.
That said, in the same way
that we've been making modern fruits sweeter,
we're making them less fibrous
in an effort to make them more palatable.
But by far the easiest way to overwhelm the liver
is by drinking fructose.
Drinking is the worst because the liver receives
a massive dose of fructose in a very short space of time
leading to high concentrations
and therefore the most damaging effects.
This is the reason that sugar-sweetened beverages
are so damaging to human health.
The evidence that sugar-sweetened beverages are associated
with obesity and type 2 diabetes is overwhelming.
And this is why many people believe
that sugar should be taxed.
Let me know in the comments down below
whether you're in favor of the idea of sugar taxation
or against it.
Given the strong association with disease,
is it any different from taxing tobacco or alcohol?
What about fruit juice or fruit smoothies.
These have long been promoted as healthy foods
and have been actively encouraged
as part of healthy eating guidelines in many countries.
The processing of these foods effectively destroys the fiber
and drinking them means your liver
gets a big hit of fructose.
We've had a small improvement in the UK healthy eating guide
as it now says to limit juice and smoothies
to one 150 mL serving a day rather than unlimited.
However, that's still 12.3 grams of sugar
when the maximum recommended daily intake of free sugar
is 30 grams for adults and 24 grams for children.
So one small glass of fruit juice
is over half of this for children,
and that is before they've even eaten anything.
Consuming fruit in the form of juice or smoothies
encourages us to drink way more
than we would naturally consume
if we ate the fruits as whole fruits.
And fruit is no longer seasonal.
Importantly, our ancestors would only eat fruits seasonally,
and occasionally honey,
and therefore they were unlikely to develop
persistent obesity.
But for us modern humans we don't have to worry
as fruit can be imported, shipped around the world,
and then the supermarket tempts us
with the colorful displays of shiny,
perfectly shaped fruits.
All types of fruit conveniently available to us
all year round.
Have a think for a moment.
In your home region or wherever you are right now,
what fruit can you see growing
and how long will it be available for?
Do let me know in the comments down below.
Fruit does of course contain
a wide variety of vitamins and minerals,
but it's nothing unique to fruit.
According to the US Food and Drug Administration,
"There is no single vitamin or mineral that is in fruit
that can't be found in meat, seafood, dairy,
nuts and seeds, whole-grains and vegetables."
So it's not like you're missing out on any special nutrition
you can't get anywhere else
if you chose to stop eating fruit.
Interestingly, whole fruits contain a number of substances
that diminish the effects of fructose, such as vitamin C,
flavonoids, and as we've already mentioned, fiber.
In some good news for moderate fruit consumption,
there is some research to suggest
that because whole fruit contains these good things,
that this actually outweighs the risks
associated with fructose consumption.
And what about glucose?
I've deliberately focused on fructose in this video,
but as I mentioned earlier, fruit does also contain glucose.
I mentioned that some fructose
is converted into glucose in the intestine.
This can also be a problem
for those of us with insulin resistance
as the elevated blood glucose levels
trigger the pancreas to produce insulin,
which in turn promotes fat storage.
And it's for this reason that I'd recommend minimizing
all of the sugars we get from fruit,
not just the fructose, if we're trying to lose weight.
And I've made another video all about this,
which I'll link to up here and at the end of this video.
So hopefully now you've a good understanding
on the uniquely toxic effects that fructose has on the body.
I want to thank Kimber Stanhope, Richard J. Johnson,
Robert Lustig, and their colleagues
for their incredible work in exposing
just how dangerous fructose is.
If you want to read more of their work,
then I'll leave some links down below in the description.
But in order to sum this up,
the sugars in fruit are natural,
not because they're any different
from the sugars in chocolate.
When you eat whole fruits they are delivered
much more slowly and along with a variety of goodies
that slows the absorption of the fructose
when compared to, for example, drinking a can of cola.
So fruit in itself is not bad,
but it's nature's way to fatten us up
to help survival in the winter months.
For those who are metabolically healthy,
it's unlikely that consuming
relatively small amounts of fruit will cause any harm.
The real issue is the amount of fructose
that we consume in the form of added sugars,
especially by drinking sugar-sweetened beverages.
I'd also add fruit juice and fruit smoothies
to that list too.
But if you're carrying extra weight and want to lose it,
or if you have other signs of insulin resistance
or type 2 diabetes, then fruit,
beyond a few berries which are very low in sugar,
is not your friend.
Thank you for watching today's video.
I really, really appreciate you being here
and watching all the way to the end.
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