Dr. Robert
H. Lustig is a pediatric endocrinologist, an expert on obesity in children and
a very talented speaker. He’s also the guy who brought the dangers of fructose
into mainstream attention.
His
presentation, Sugar: The Bitter Truth, is
a 90 minute lecture that delves deep into the science and biochemistry behind
fructose consumption, with 3 million views.
Why is
Fructose Bad For You? Some Important Points
Sugar
(sucrose) and High Fructose Corn Syrup both supply a significant portion of the
total calories in a standard western diet.
They both
consist of two simple sugars… glucose and fructose.
Glucose also
comes from starches like potatoes, our bodies produce it and every cell on the
face of the earth has glucose in it. Glucose is a molecule absolutely vital to
life.
Fructose
however, is not. Humans don’t produce fructose and throughout evolutionary
history have never consumed it except seasonally when fruit were ripe.
Glucose and
fructose are metabolized very differently by the body.
The key
thing to realize, is that while every cell in the body can use glucose, the
liver is the only organ that can metabolize fructose in significant amounts.
When people
eat a diet that is high in calories and high in fructose, the liver gets
overloaded and starts turning the fructose into fat.
Lustig and
other scientists believe that excess fructose consumption may be a key
driver of many of the most serious diseases of today, including: obesity,
type II diabetes, heart disease and even cancer.
The Harmful
Effects of Excess Fructose
Eating a lot
of fructose in the form of added sugars may:
- Make your liver synthesize
fats, which are exported as VLDL cholesterol, which leads to dyslipidemia
(blood tryglicerides and cholesterol), fat around the organs and
ultimately, heart disease - Increase blood levels of uric
acid, leading to gout and elevated blood pressure. - Cause deposition of fat in the
liver, potentially leading to non-alcoholic fatty liver disease. - Cause insulin resistance,
which ultimately leads to obesity and type II diabetes. - Insulin resistance leads to
elevated insulin and insulin like growth factor (IGF-1) in the entire
body, which may ultimately cause cancer. - Fructose doesn’t affect satiety
in the same way as glucose, making you eat more total calories
automatically if your fructose intake is high. - Excess fructose consumption may
cause leptin resistance, throwing body fat regulation out of whack
and contributing to obesity. - Sugar may be downright addictive.
Leptin
resistance, elevated insulin and vicious addictive cycles of cravings and binge
eating are a recipe for fat gain disaster.
If
potentially leading to obesity, cancer, heart disease and diabetes isn’t reason
enough to stop eating added sugars, I don’t know what is.
Be aware
that not all of this has been proven beyond a shadow of a doubt in
controlled trials, but the evidence is still very strong and more
studies will paint a clearer picture in the coming years and decades.
Fructose
From Added Sugars is Bad For You, Fruit is NOT
It’s
important to realize that all of this does NOT apply to fruit.
Fruits
aren’t just watery bags of fructose, they are real foods with a low energy
density and lots of fiber.
They’re hard to overeat on and you’d have to eat ridiculous amounts to reach
harmful levels of fructose. In general, fruit is a minor source of fructose in
the diet compared to added sugars.
The harmful
effects of fructose apply to a western diet supplying excess calories and added
sugars. It does NOT apply to the natural sugars found in fruits and vegetables.
Period.
source : http://authoritynutrition.com/why-is-fructose-bad-for-you