Flashback Friday: What Causes Insulin Resistance and Diabetes?
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Flashback Friday: What Causes Insulin Resistance and Diabetes?


“What Causes Insulin Resistance and Diabetes?” Studies dating back nearly a century
noted a striking finding. If you take young, healthy people
and split them up into two groups, half on a fat-rich diet, and the
other half on a carb rich diet, within just two days,
this is what happens. The glucose intolerance
skyrockets in the fatty diet group. In response to the same
sugar water challenge, the group that had
been shoveling in fat ended up with twice
the blood sugar. As the amount of fat in the diet goes
up, so does one’s blood sugar spikes. It would take scientists nearly seven
decades to unravel this mystery, but it would end up holding the key to
our current understanding of the cause of type 2 diabetes. When athletes carb load before a
race, they’re trying to build up the fuel supply
within their muscles. They break down the starch into
glucose in their digestive tract; it circulates as blood
glucose, blood sugar, and is taken up by our muscles
to be stored and burned for energy. Blood sugar, though,
is like a vampire. It needs an invitation
to come into our cells. And that invitation is insulin. Here’s a muscle cell. Here’s some blood sugar outside
waiting patiently to come in. Insulin is the key
that unlocks the door to let the sugar in our blood
enter the muscle cell. When insulin attaches
to the insulin receptor, it activates an enzyme, which
activates another enzyme, which activates two more enzymes,
which finally activates glucose transport, which acts as a gateway
for glucose to enter the cell. So insulin is the key that unlocks
the door into our muscle cells. What if there was
no insulin though? Well, blood sugar would be
stuck out in the bloodstream banging on the door to our
muscles and not be able to get inside, and so with nowhere to go,
sugar levels would rise and rise. That’s what happens
in type 1 diabetes. The cells in the pancreas
that make insulin get destroyed, and without insulin,
sugar in the blood can’t get out of the blood into the muscles,
and blood sugar rises. But there’s a second way we could
end up with high blood sugar. What if there’s enough insulin,
but the insulin doesn’t work? The key is there but something’s
gummed up the lock. This is called insulin resistance. Our muscle cells become
resistant to the effect of insulin. What’s gumming up the door
locks on our muscle cells preventing insulin
from letting sugar in? Fat. What’s called
intramyocellular lipid, fat inside our
muscle cells. Fat in the bloodstream can build
up inside the muscle cell, creating toxic fatty
breakdown products and free radicals that can block
the signaling pathway process. So no matter how much insulin
we have out in our blood, it’s not able to open
the glucose gates, and blood sugar levels
build up in the blood. This mechanism by which fat,
specifically saturated fat, induces insulin resistance wasn’t known until fancy MRI
techniques were developed to see what was happening
inside people’s muscles as fat was infused
into their bloodstream. That’s how they found out that
elevation of fat levels in the blood causes insulin resistance by inhibition
of glucose transport into the muscles. And this can happen
within just three hours. One hit of fat can start
causing insulin resistance, inhibiting glucose uptake
after just 160 minutes. Same thing happens
to adolescents. You infuse fat into
their bloodstream. It builds up in their muscles and
decreases their insulin sensitivity, showing that increased
fat in the blood can be an important contributor
of insulin resistance. And then you can do
the opposite experiment. Lower the level of fat
in people’s blood and the insulin resistance
comes right down. Clear the fat out of the blood, and
you clear the sugar out of the blood. So that explains
this finding. On a high fat diet, the ketogenic diet,
insulin doesn’t work as well. Our bodies are
insulin resistant. But as the amount of fat in
our diet gets lower and lower, insulin works
better and better. This is a clear demonstration
that the sugar tolerance of even healthy individuals
can be impaired by administering a
low-carb, high-fat diet. But we can decrease insulin resistance,
the cause of pre-diabetes, the cause of type 2 diabetes,
by decreasing saturated fat intake. After about age 20, we may have all
the insulin-producing beta cells we’re ever going to
have in our pancreas, and so if we lose them,
we may lose them for good. Autopsy studies show that by the
time type 2 diabetes is diagnosed we may have already killed
off half of our beta cells. You can do it right in a Petri dish. Expose human beta cells to fat, they suck it up, and
then start dying off. A chronic increase in blood
fat levels is harmful as shown by the important effects
in pancreatic beta cell lipotoxicity. Fat breakdown products can interfere
with the function of these cells and ultimately lead to their death. And not just any fat, saturated fat. The predominant fat in
olives, nuts, and avocados gives you a tiny bump
in death protein 5, but saturated fat really ramps up
this contributor to Beta cell death. Saturated fats are harmful to b-cells,
harmful to the insulin-producing cells in our pancreas. Cholesterol, too. The uptake of bad cholesterol, LDL,
can cause Beta-cell death as a result of free radical formation. So diets rich in saturated fats not only
cause obesity and insulin resistance, but the increase levels of
circulating free fats in the blood, called NEFAs, non-esterified
fatty acids, causes Beta-cell death
and may thus contribute to progressive Beta-cell
loss in type 2 diabetes. And this isn’t just based
on test tube studies. If you infuse fat into
people’s blood stream you can directly impair
pancreatic Beta-cell function, and the same when we ingest it. Type 2 diabetes is
characterized by defects in both insulin secretion
and insulin action, and saturated fat
appears to impair both. Researchers showed
saturated fat ingestion reduces insulin sensitivity
within hours, but these were non-diabetics, so their
pancreas should have just been able to boost insulin secretion to match, but insulin secretion
failed to compensate for insulin resistance in subjects
who ingested the saturated fat. And this implies the saturated fat
impaired beta cell function as well, again within just hours after
it going into our mouth. So increased consumption
of saturated fats has a powerful short- and
long-term effect on insulin action, contributing to the
dysfunction and death of pancreatic beta
cells in diabetes. And saturated fat isn’t
just toxic to the pancreas. The fats found predominantly in
meat and dairy — chicken and cheese are the two main sources
in the American diet — are almost universally toxic,
whereas the fats found in olives, nuts, and avocados are not. Saturated fat has been
found to be particularly toxic to liver cells in the formation
of fatty liver disease. You expose human liver cells
to plant fat and nothing happens. Expose liver cells to animal
fat and a third of them die. This may explain why higher intakes
of saturated fat and cholesterol are associated with
nonalcoholic fatty liver disease. By cutting down on
saturated fat consumption we may be able to help
interrupt this process. Decreasing saturated
fat intake may help bring down the need for
all that excess insulin. So either being fat or
eating saturated fat can both cause that excess
insulin in the blood. The effect of reducing dietary
saturated fat intake on insulin levels is substantial, regardless of how much
belly fat we have. And it’s not just that by eating fat we
may be more likely to store it as fat. Saturated fats, independently of
any role they have making us fat, may contribute to the development of insulin resistance and all
its clinical consequences. After controlling for weight, and alcohol, and smoking,
and exercise, and family history, diabetes incidence was
significantly associated with the proportion of
saturated fat in our blood. So what causes diabetes? The consumption of too many
calories rich in saturated fats. Now just like everyone who smokes
doesn’t develop lung cancer; everyone that eats a lot of saturated
fat doesn’t develop diabetes. There’s a genetic component, but just like smoking can
be said to cause lung cancer, high calorie diets
rich in saturated fats are currently considered
the cause of type 2 diabetes.

73 Comments

  • yangtse55

    I got insulin resistant on a 39 year WFPB diet with added recreational carbs. It was OBESITY that caused it and losing 10kg fixed it
    Carbs DO make you fat.

  • Sadiq Hussain

    It's hard to believe these You tube docs…Wonder who is speaking the truth??? Keto, Carnivorous or WFPB ??? Or are these docs simply competiting against each other while making us Fools !

  • G F

    This solved my (true to life) explanation of just how type 2 diabetes comes about. No more saturated fats for me, I'm too old to fight it. Thank you so very much.

  • Luke Weaver

    So coconut oil is more damaging than flax or hemp oil? I always try to add plenty of fiber with high fat, natural, unprocessed foods such as avocado (which are naturally high in fiber anyway). Also take non GMO sunflower lecithin in the morning with my smoothie and/or nuts/nut butter (almond, pistachio, cashew, coconut on flax bread). Still getting 75-100 grams/fiber per day plus fresh veggie juice daily to scrub and energize.

  • Jai White

    Everything he tries to blame on saturated fats is actually caused by sugars/glucose/simple carbs.

    People reverse their T2D all the time by going low carb and/or healthy keto.

  • Daily D

    Lmao.. Ya saturated fats the cause of type 2 diabetes? It couldnt possibly be the sugars.. Breads.. High glycemic foods that are causing it…. Give me a break. I feel and look the best when i eat all meat and no veggies.

  • В отрыв!

    Hello, Michael ! I don’t drink or smoke, I walk 8000 steps daily. I completely switched to plant-based nutrition, but my cholesterol level does not fall. Total cholesterol – 247, LDL – 150. I follow a plant diet for about half a year. I tried to take Biologically Active Additives (garlic, curcumin, magnesium ), but nothing helps. Why does cholesterol not fall?

  • Sunghee Lee

    I have a neighbor who has her 7years old just got diagnosed with type 2 diabetes.
    His diet is consistent of meat, dairy and sweets…😢

  • yangtse55

    Time to unsubscribe from NF again methinks …. so depressing to hear the "What The Health" propaganda still being trotted out.
    When I first heard Barnard spouting the fat versus carbs nonsense years ago, I had no idea what diabetes was.
    Perhaps it was actually a good thing that I briefly experienced it myself so was forced to find out how it actually works.
    https://www.youtube.com/watch?v=6vsrB_dlUzI
    For the record my core diet has been WFPB for nearly 40 years and will obviously continue.

  • Winston Smith

    What a lying-a– piece of s–t. It's clear this doofus's site, "NurtritionLies.org", has one agenda only … to keep everyone sick. This video is a complete lie.

  • Rabbit Food Fitness

    Thanks for the awesome video! People really need to know what is actually behind diabetes. Your videos always inspire me to keep posting on my channel!

  • monkeygirl000

    I can’t say, for sure, if I’m insulin resistant (all blood work always comes back normal), but I was diagnosed with PCOS in my 20s (30 years ago), and PCOS is apparently associated with insulin resistance.

    I was naturally very thin (BMI 16-17) (a fairly rare, but known, sub-set of PCOS sufferers) for 3 decades. Then, suddenly, I began gaining weight. I gained about 10lbs in maybe a month! In retrospect, it is clear this was the onset of perimenopause. And because this is a hormonal cause of weight gain, it does not respond the same way to traditional weight loss strategies.

    I was struggling. I’d never needed to lose weight before, and even exercising for hours/day and fasting for days, did not lead to significant or sustained weight loss. Anything less than fasting and gruelling daily workouts permitted incremental weight gain to continue (i.e. always +0.10lb, at least, every day).

    Long story short, after years with continued weight gain despite apparent caloric deficit, it was actually an online PCOS forum that gave me a strategy that worked: 3g of daily cinnamon. And it worked; from the very first day I added cinnamon, I started losing weight, in contrast to years of failure. In 3 months with cinnamon, I’d lost 30 lbs. (I’m a science-y type, so I had a weight graph. 🤣 It went from a gradual incline, to a virtual free-fall, starting the day I added cinnamon.)

    To be fair, the effect levelled off, and I haven’t seen results as dramatic as those first 3 months. I tried cinnamomum verum, to avoid the toxic coumarin in cinnamomum cassia, but found it had no effect. (I later learned research backs that up.) Also, PCOS is said to cause up to a 30% reduction in BMR. Indeed, my BMR is under 1,000 (which explains why even 4 days of fasting doesn’t register a single pound lost, given the accompanying water retention).

    Cinnamomum cassia can improve insulin sensitivity in those who are insulin resistant. With diet and exercise, this can assist with weight loss. Of course, we now know insulin resistance, in people with normal metabolisms, is caused by excess intramyocellular fat. So…yeah…also eat a WFPB diet. (Myself, I was vegan, eating a pretty healthy diet, all that time.)

    Because my diagnosed PCOS didn’t actually cause me any difficulties all those decades (beyond irregular menstrual cycles), I never really looked into it. Turns out, PCOS is associated with insulin resistance. So, it makes perfect sense that this tactic worked for me, with my combination of PCOS and perimenopausal weight gain.

    My real message is, never go through perimenopause 🤣 …and if you have PCOS-related insulin resistance and need to lose some weight, consider trying 3g of cassia cinnamon/day, for a brief period, and see if that helps.

  • Marie LeVasseur Brown

    This is interesting to me and has come at a perfect time. I couldn’t figure out why my morning sugar reading was so inconsistent. After dinners of multigrain pasta or multigrain breads, my morning sugar reading was under 120. After a day of and dinner of saturated fats and no multigrain pastas and breads, my reading is over 150. Makes total sense to me now.

  • Relax Good

    Keto and Carnivore diets are suppported by nothing but talk and are a huge roll of the dice for those you do it. None of the longest lived studied people on the earth eat either a Keto or Carnivore Diet and those who do are counting on fantasy land theories to make them feel good about it. When you don’t like the answer to a healthy diet you go Keto or Carnivore.

  • Jeff Eppenger

    I'm curious how does the body know the difference between plant-based saturated fat vs an animal-based saturated fat? So would the relationship between someone with elevated cholesterol and diabetes mean that if you have higher cholesterol levels then your at even higher risk for diabetes? Genetic factors seem to be the main cause. Elevated lipids are an issue for me even while on a whole food diet. Genetics play a role here so I'm taking statins. So am i at higher risk for diabetes?

  • Tom G

    It's more complex than that, a recznt study showed that different people react different to different foods. For some they have thus effect for some not

  • José Manuel Rivero Rodríguez

    I am diabetic type 2 and I already have two years with keto diet and intermitent fasting. Before I used to inject 60 units of insuline daily and my A1c was a high 13. Now I left behind all diabetic pills and insuline dosis and my A1c is a low 5.2. So I do not understand this video. It is said exactly the oposite of what I have lived during these last two years.

  • Fist of Fury

    What about dr Terry whals diet. She eats a diet of meat and vegetables. Low carb vegetables. Uses coconut oil and lot. Has reversed MS, and has no diabetes issues. Her diet consist mainly of fats. She is also running clinical trials using her diet to reverse autoimmune issues and ms. So how about that? Please check her out Dr Terry Whals. The Terry Whals protocol.So something does not make sense here. More research needed maybe?

  • Rob Williams

    Hyenas scream about people not accepting climate science (which is indead absurd and horrendous), but in nutrition we have countless identical examples that people buy into who pride themselves on being woke on all kinds of other stuff. Somehow even smart people cannot understand what this video covers. Sugar causes diabetes is what they say. This might help, but sadly, probably not. I liked it!

  • Dwarf Giant

    In my nearly 80 years of life, they reinvent names to fat and meat rich diets to continue the lie. Common knowledge has never changed: the less meat, fat, dairy and/or junk foods the better. I can attest it. The only difference is that I didn't know that it could 0% animal products until 20 years ago.

  • Jasmine Usoro-Brown

    Dr Greger and Dr Fung have completely different outlooks on controlling insulin resistance. Does anybody have any opinions on this? As I'm so confused at which evidence and theory to believe

  • J B

    I truly believe that Dr. Greger's whole, plant based diet is the way to go, but there seems to be a lot of Keto people claiming that it their diet controls diabetes…is that only because they eat very low carb?

  • Joseph1NJ

    So why isn't there an acute rise in type II diabetes in all the high fat keto dieters? Many of these people have eating this way for years and swear by it.

  • Геннадий Счастливый

    thank you very much for your work. I have only one question for you: how do you feel about the anti-vaccination movement and the vaccine in General?

  • Caleb Hicks

    I'm very thankful for this video. It is exactly what I need to show my recently diagnosed diabetic father. He doesn't believe me when it comes out of my mouth but he said he'd be willing to listen to my sources for himself. So between Dr. Greger and Dr. Barnard he should be alright.

  • The Verbally Abusive Clown

    Fast food restaurants MUST be wiped from the face of the Earth and humans MUST…uh…hold on…just lost my train of thought…uh…oh yeah! Humans MUST become more smarter about proper nutrition! Nailed it.

  • seahog32

    I don't subscribe to the keto hype but even if a high fat and close to zero carb diet does indeed lead to increased insulin resistance of peripheral tissues, this is not a cause of hyperglycemia, hence no diabetes. The insulin resistance in this case is a physiological reaction to spare the glucose for neurons, red blood cells and whatever other cells there are that can't survive on fat (or mostly on fat I should say) and at the same time to spare the muscle tissue from effects of excessive gluconeogenesis. Certainly though if the fat intake long-term exceeds the amount the body needs as energy source, the excessive fat will be stored and the portion of it stored in muscles will lead to lasting insulin resistance (and obesity as well of course). However, as long as the blood glucose levels are maintained almost exclusively by gluconeogenesis, as it is in cases of a strict keto diet, DM cannot develop. Further on, any excess of carbohydrate intake beyond what covers body energy needs is converted into lipids which again lead to increased insulin resistance, however in this case in combination with readily available blood glucose and a result of situation typical for type 2 diabetes. Thus the conclusion again is that neither fat nor the sugars are a cause of type 2 DM but rather the excessive energy intake in any macronutrient form, aka overeating.

    Had to look it up, but there are plentiful studies describing pancreatic beta cells proliferation both in rodent and in human models, so it is not true that beta cells once lost are necessarily lost for ever.

    The studies cited in this video are indeed talking about high fat intake effects on muscle cells, but not high fat/low carb diet as such, so they cannot be used as an argument against the keto diet (which I again don't follow and think it is unhealthy for many different reasons).

  • Tedel James

    These studies were a revelation to me as I had no idea that fat affected insulin and blood sugar in any way. I´m interested in how intake of simple sugar interacts with high fat in increasing liver and heart disease, diabetes. I wish I hadn´t ignored the sciences during my pre and post grad years.

  • M. Fender

    Does anybody know if beta cells are destroyed by saturated animal fats if we strictly avoid carbs? Or is just the combinations of carbs plus fats that causes all these devastating effects? If Michael Greger is right ALL long-term keto dieters should have destroyed pancreases! Is this really the case? Probably not.

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