Why Fructose causes insulin resistance | Insulin Resistance | Jason Fung
Summary
TLDRThis video explores the detrimental effects of sugar, particularly fructose, on weight gain and type 2 diabetes. Unlike glucose, which is utilized by all body cells, fructose is exclusively metabolized by the liver, leading to fat production and contributing to fatty liver, insulin resistance, and metabolic syndrome. The script highlights studies showing the correlation between sugar-sweetened beverages and increased risk of weight gain and type 2 diabetes, emphasizing the importance of reducing sugary foods and beverages in weight loss and diabetes management.
Takeaways
- 🍬 Sugar, particularly in the form of sucrose (table sugar), is more harmful than other carbohydrates due to its composition of glucose and fructose.
- 🔍 Different types of sugars, such as glucose, fructose, and lactose, have distinct impacts on the body, with fructose being especially concerning for health.
- 📈 High consumption of sugar-sweetened beverages has been linked to increased weight gain and a higher risk of developing type 2 diabetes.
- 🚫 Fructose does not raise blood glucose levels, which previously led to the misconception that it was a healthier alternative to glucose.
- 🍇 Fructose is naturally found in fruits and was once considered healthy, but recent studies have shown its negative effects on the body.
- 🧬 The metabolism of fructose is unique as it is primarily processed by the liver, unlike glucose which can be used by nearly every cell in the body.
- 💉 Excessive fructose intake can lead to the development of fatty liver, which in turn causes insulin resistance and increases the risk of type 2 diabetes.
- 📉 Studies have shown that fructose consumption can worsen insulin resistance by up to 25% compared to glucose.
- 🍞 Low carbohydrate diets can be effective for managing type 2 diabetes as they replace glucose with fats and proteins.
- 🍎 While fruits contain fructose, they should be consumed in moderation, especially for those trying to lose weight or manage type 2 diabetes.
- 🔑 The key to managing weight and type 2 diabetes includes reducing intake of sugary foods and being mindful of the fructose content in even seemingly healthy options.
Q & A
Why is sugar considered more deadly than other carbohydrates in terms of weight gain and type 2 diabetes?
-Sugar, specifically sucrose, is a combination of glucose and fructose. While glucose can be metabolized by every cell in the body, fructose is primarily processed by the liver and can lead to increased fat production, insulin resistance, and consequently, a higher risk of weight gain and type 2 diabetes.
What are the different types of sugars mentioned in the script?
-The script mentions glucose, fructose, lactose, and sucrose (table sugar) as different types of sugars. Glucose is a component of many carbohydrates, lactose is milk sugar, and sucrose is a combination of glucose and fructose.
Why were low-carbohydrate diets considered effective for treating type 2 diabetes?
-Low-carbohydrate diets can be effective in treating type 2 diabetes because they focus on consuming fats and proteins instead of glucose. This helps to prevent the rapid increase in blood glucose levels that can occur with the consumption of high amounts of refined carbohydrates.
What was the historical perspective on fructose according to the script?
-Historically, fructose was thought to be healthy. For example, in 1986, the FDA stated there was no conclusive evidence that sugar demonstrated a hazard, and as recently as 2006, the American Diabetes Association suggested that sucrose could be substituted for any other carbohydrate in a meal plan.
What evidence started to change the perception of fructose as being healthy?
-Studies in the mid-2000s, such as the Nurses' Health Study conducted by the Harvard Medical Center, provided conclusive evidence that fructose is likely much worse than regular glucose, especially in terms of its contribution to weight gain and the risk of type 2 diabetes.
How does the consumption of sugar-sweetened beverages correlate with weight gain and type 2 diabetes risk?
-The Nurses' Health Study found a clear correlation between the consumption of sugar-sweetened beverages and both weight gain and the risk of type 2 diabetes. The more frequently these beverages were consumed, the higher the risk and weight gain.
Why is fructose considered worse than glucose for health?
-Fructose is considered worse than glucose because it is metabolized almost exclusively by the liver, which can lead to the conversion of fructose into fat, particularly in the liver, contributing to fatty liver disease, insulin resistance, and an increased risk of metabolic syndrome and type 2 diabetes.
What is the process that occurs when fructose is metabolized in the liver?
-When fructose is metabolized in the liver, it can be converted into triglycerides through a process called lipogenesis, which is the creation of new fat. This can lead to fatty liver and central adiposity, contributing to metabolic syndrome.
How does fructose consumption affect insulin resistance?
-High fructose consumption can lead to increased insulin resistance, as shown by studies where insulin tolerance tests comparing glucose to fructose showed a significant worsening of insulin resistance with fructose.
What advice does the script give for managing weight and type 2 diabetes?
-The script advises cutting down on sugary foods and added sugars, and even being cautious with fruits that can be high in fructose, as part of a strategy to manage weight and type 2 diabetes.
What is the role of the liver in metabolizing fructose?
-The liver is the primary organ responsible for metabolizing fructose. Unlike glucose, which can be used by every cell in the body, fructose is processed almost exclusively by the liver, where it can be converted into fat if not needed for energy.
Outlines
🍬 The Destructive Impact of Sugar on Weight and Health
This paragraph delves into the detrimental effects of sugar, particularly in the context of weight gain and type 2 diabetes. It explains the scientific perspective on various sugars, including glucose, fructose, and lactose, and their roles in carbohydrate metabolism. The focus is on the glycemic impact of refined carbohydrates like bread and pasta, which are primarily glucose chains, and how their consumption can significantly raise blood glucose levels. The narrative shifts to the discussion of sucrose, or table sugar, which is a combination of glucose and fructose, and historically considered less harmful due to fructose's natural presence in fruits and its non-glycemic nature. However, recent studies, such as the Nurses' Health Study, have linked high fructose corn syrup and sugar-sweetened beverages to increased weight gain and a higher risk of type 2 diabetes, challenging the previously held belief in fructose's safety.
🍏 The Metabolic Consequences of Fructose Intake
The second paragraph examines why fructose is more harmful than glucose, despite both being sugars with similar caloric content. The key difference lies in their metabolism; glucose can be utilized by every cell in the body, whereas fructose is exclusively metabolized by the liver. This unique pathway leads to fructose being converted into fat, particularly contributing to fatty liver, central adiposity, and metabolic syndrome. The paragraph highlights studies that demonstrate fructose's role in increasing insulin resistance, a precursor to type 2 diabetes, and how it exacerbates the condition by causing the liver to produce more glucose than needed, leading to lipogenesis. The conclusion emphasizes the importance of reducing sugary foods and even high-fructose fruits in one's diet to manage weight and type 2 diabetes effectively.
Mindmap
Keywords
💡Sugar
💡Weight Gain
💡Type 2 Diabetes
💡Carbohydrates
💡Glucose
💡Fructose
💡Sucrose
💡Glycemic Index
💡Lipogenesis
💡Insulin Resistance
💡Metabolic Syndrome
Highlights
Sugar is considered more deadly in terms of weight gain and type 2 diabetes than other carbohydrates.
Different types of sugars include glucose, fructose, and lactose, with glucose being a primary component in many foods.
Highly refined carbohydrates like bread raise blood glucose levels due to their glucose content.
Low carbohydrate diets can be effective for type 2 diabetes treatment by reducing glucose intake.
Sucrose, or table sugar, is a combination of glucose and fructose with distinct structures and effects.
Fructose was once considered healthy due to its natural presence in fruit and its sweetness.
Recent studies have shown that fructose is worse than glucose, contradicting past beliefs.
High fructose corn syrup has been linked to health issues, including weight gain and type 2 diabetes.
The Nurses' Health Study provided evidence of a correlation between sugar-sweetened beverages and weight gain.
Increased consumption of sugar-sweetened beverages is associated with a higher risk of type 2 diabetes.
Fructose metabolism differs from glucose, being processed primarily by the liver and leading to fat production.
Fructose intake can result in fatty liver, central adiposity, and metabolic syndrome.
Studies have shown that fructose causes more insulin resistance compared to glucose.
Fructose metabolism can lead to a diagnosis of insulin resistance in healthy individuals.
Cutting down on sugary foods and added sugars is key for weight loss and managing type 2 diabetes.
Even fruits, which can be high in fructose, may not be ideal for weight loss or diabetes management.
Transcripts
today we're going to talk about why
sugar is so deadly in terms of weight
gain and type 2 diabetes and much worse
than potentially any other carbohydrate
that's out there and it's coming right
up
when we talk about sugar from a
scientific standpoint there's lots of
different sugars other than what we
think about in terms of table sugar
those are the things that generally end
in oaths like glucose fructose and
things like milk sugar which is lactose
when we talk about carbohydrates they
are generally long chains of glucose so
when you're talking about rice potatoes
flour like bread or pasta for example
those are mostly glucose when we talk
about blood sugar we talk about blood
glucose and that's one of the reasons
why eating highly refined carbohydrates
like
bread can raise your blood glucose very
high because you're eating
long chains of glucose the minute they
get broken down the glucose level in the
blood goes up so that's why low
carbohydrate diets can be very effective
in the treatment of type 2 diabetes
because you're eating fats and proteins
as opposed to glucose
however there's another sugar which we
think about is
sucrose which is table sugar we use it
in baking we use it in many types of
things and that's not glucose it's
actually a combination of one molecule
of glucose and one molecule of fructose
they are slightly different in terms of
their structure but they are both
classified as sugars as are things like
lactose
fructose is naturally found also in
fruit and in fact is one of the sweetest
sugars that can be around
for many many years people thought
fructose was actually healthy for you
in 1986 for example the uh
fda said that there was no conclusive
evidence that sugar demonstrates a
hazard even as recently as 2006 the
american diabetes association said you
can substitute sucrose for any other
carbohydrate in the meal plan so that
was meaning that fructose wasn't
particularly bad for you because
remember sucrose is one glucose one
fructose that glucose is the same as any
other glucose but the fructose is very
different
the question is why it's so bad for you
it doesn't
raise the glycemic index because the
blood glucose doesn't go up when you eat
fructose because that's a completely
different type of sugar
and the other thing is that it's very
sweet and it's found naturally in fruit
so for many years people thought it was
quite
healthy for you to substitute fructose
for glucose
recently though it's become very clear
that this has been a very bad swap
there's been a lot of talk about high
fructose corn syrup and how that is very
bad for you
in the mid 2000s
studies such as the nurses health study
in 2004 started to demonstrate
conclusive evidence that fructose is
probably much worse than regular glucose
this nurse's health study was run by the
harvard
medical center and it followed many
thousands of nurses
documented their habits and compared
them to what happened
when they looked at sugar sweetened
beverages for example from 1991 to 1999
they looked at the correlation between
weight gain and whether people drank
sugar sweetened beverages regularly you
can see that both those that did drink
it and didn't drink it gained on average
about 2 kilos
over that period of time
and it was true whether they drank a
little bit of soda or a lot of soda
however what's more interesting is that
when you switch
from drinking less than one per week to
more than one per day
the weight gain almost doubled
when you did the opposite when you went
from consistently drinking more than one
a day to less than one a week the weight
gain practically vanished so there was
clearly a correlation which was more
than just calories between sugar
sweetened beverages and weight gain and
the true this was also true for type 2
diabetes so if you look at the number of
sugar sweetened beverages the nurses
drank per month
as you drank more and more of these
sugar sweetened beverages the risk of
type 2 diabetes simply goes up and up
and up
and this is
especially bad because of course the two
go together but the type 2 diabetes puts
you at very high risk of other diseases
like heart diseases and strokes
the question is why is the fructose so
especially bad for you much more than
the glucose both are molecules of sugar
both are sweet both have roughly the
same number of calories
the difference is the way that the
fructose is metabolized and glucose can
be used by every cell in the body
so if you're eating
50 grams of carbohydrates say a slice of
bread or something like that
all of your cells in your body your
heart your liver your brain
all
of it can use glucose so if you weigh
180 pounds all 180 pounds of your body
can metabolize that glucose this is not
true however for fructose
when you eat the same amount of fructose
none of your body except for the liver
can actually metabolize that fructose so
your your heart your liver your kidneys
they can't use that fructose in fact the
only place that it can go is straight
into the liver
and when it goes into the liver what
happens is that it turns into fat
looking at this diagram
what you see is that the fructose
is absorbed through the intestines goes
straight into the liver so instead of
all 180 pounds of body using up the
glucose you have maybe five pounds of
the liver metabolizing that fructose and
it can get turned into glucose however
if you're eating a lot of carbohydrates
or if you're eating sucrose which
already has glucose your body doesn't
need more of that glucose so that's one
way that it can be metabolized that's
blocked off the only other way it can go
is get turned into triglycerides which
is a process called lipogenesis or the
creation of new fat
what you get is fatty liver and then the
body tries to deliver tries to export
that fat out through vldl so you get
central adiposity and the metabolic
syndrome so in fact the fructose is much
much worse for you because there's
simply no way to get rid of it all as
opposed to using the the rest of the
body to metabolize it
several studies had shown very early on
that when you compare glucose to
fructose you get much more of this
insulin resistance because of that fatty
liver
we talked about fatty liver in the past
and how it's very closely related to
insulin resistance which then causes
type 2 diabetes it turns out that if you
do a insulin tolerance test
comparing a dose of glucose to a dose of
fructose you get about 25 worsening of
insulin resistance
in 2009
in the
jci they published a very interesting
study where again they looked at giving
people glucose versus giving them
fructose and even these normal healthy
volunteers when they get the fructose
their blood glucose levels goes up to a
point that you can actually diagnose
insulin resistance
so the high insulin resistance then
causes high insulin levels in order to
try to metabolize it you get the fatty
liver and there that starts you on the
pathway towards
metabolic syndrome type 2 diabetes and
weight gain so when you're looking at
the fructose versus the glucose you have
to recognize that the fructose the way
that it's metabolized is makes it much
much more likely to get turned into fat
to get turned into the bad type of fat
which is the liver fat
and that causes the insulin resistance
which gives you this very high rate of
type 2 diabetes so really
the key if you're starting to lose
weight is really to cut down those
sugary foods especially the added sugars
even the fruits which can be very high
in fructose sometimes are not your best
friend if you're trying to lose weight
or manage type 2 diabetes thanks very
much for watching
see you next week
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