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Does a Keto Diet Cause Diabetes?

Does a Keto Diet Cause Diabetes?
  • A recent study found that a ketogenic diet caused pre-diabetes in mice, and a lot of nutrition outlets are questioning whether keto causes diabetes in humans. (It doesn’t!)
  • Problem is, mice evolved to eat almost exclusively carbohydrate-rich grains and are a notoriously bad way to study high-fat diets.
  • A lot of human studies have found that ketosis is great for diabetes, to the point where diabetics can get off their medication entirely.
  • However, long-term keto may not be a good idea because it can compromise your metabolic flexibility. Studies show that long term ketosis can cause reversible insulin resistance.
  • Cyclical ketosis, where you load up on carbs once a week, is the best way to feel great all the time and become resilient and metabolically flexible.

There’s a rumor going around that a keto diet causes diabetes. Part of it is thanks to this study, which found that mice fed a ketogenic diet developed insulin resistance, a precursor to diabetes, and couldn’t tolerate reintroducing carbs into their diet.

A few prominent health and nutrition news outlets have used the study as evidence that keto may cause diabetes, and say you’re better off avoiding the high-fat, low-carb diet.[1][2]

Here’s the short version of this article upfront: keto does not cause diabetes. In fact, several human studies have found that keto reverses diabetes to the point where diabetics can stop taking insulin (more on that below).[3][4][5]

That said, long-term ketosis without any carbs does contribute to insulin resistance, and it’s not the best way to boost your performance. That’s why Bulletproof promotes a cyclical ketogenic diet that puts you in and out of ketosis, with one day a week of low-glycemic, non-junk carb loading

At the end of this article, you’ll learn exactly how you can balance ketosis and carbs to maximize your metabolic flexibility. Metabolic flexibility, by the way, is the body’s ability to shift back and forth between burning carbs (or glucose) and fatty acids for fuel. First, let’s take a closer look at the claim that keto can lead to diabetes.

Does a keto diet really cause diabetes?

keto diet and diabetesAt first glance, it seems like there’s a chance keto really does lead to diabetes. The study[6]  people have been citing lately went like this:

  • The researchers took three groups of mice and fed them either a high-carb diet, a keto diet, or an obesogenic diet (a high-carb and high-fat diet designed to make mice obese).
  • The low-fat mice did just fine, but both the keto and obesogenic mice developed glucose intolerance — an inability to process carbs well — after just three days on their new diets.
  • The keto mice also developed insulin resistance in their livers. Insulin resistance is the first step toward diabetes.

Relying on this data from mice, it doesn’t look good for keto.

And it’s not just this study, either. Several other studies have found  that keto leaves rodents unable to process carbs,[7] leads to insulin resistance,[8] and, more long-term, causes non-alcoholic fatty liver disease, which is when your liver accumulates lots of fat and begins to shut down.[9][10] Triglycerides and inflammation go way up, too.[11]

But before you give up your Bulletproof Coffee and sink your teeth into a bagel, let’s talk about something all these studies have in common: they’re in rodents. And rodents are very different from people.

Even more alarmingly, scientists seem to believe that all types of fat are the same, when we all know that a high-margarine diet will do very different things than a high coconut oil diet, even though they are both high-fat diets. Mouse chow doesn’t usually use high-quality fats.

People do much better with keto than mice do

keto diet and diabetesThe problem with all this research is that mice are notoriously bad models for high-fat diets. Check out this scientific statement from a nutritional study back in 2012:

“As a model of human obesity and insulin resistance, [mice] suffer from the severe, if under-emphasized, limitation that high-fat diets do not generally cause these conditions in humans, unless high-carbohydrate is also present.”[12]

In other words, high-fat diets make mice fat and pre-diabetic, but they don’t do the same thing to people. They do just the opposite:

  • Keto decreases glucose intolerance and stabilizes insulin so well that a lot of diabetics can get off their medication entirely after switching to a keto diet.[13][14][15][16][17][18][19] Keto functionally cures their diabetes.
  • Keto decreases inflammation and improves brain function — so much so that Alzheimer’s patients who switch to a keto diet actually begin to recover their brain function, which up until now was unheard of.[20][21][22][23][24] So there’s that. (Dale Bredesen and Mark Hyman have discussed these on the Bulletproof Radio podcast. Check out Dale’s episode here, and Mark’s here.)  

Clearly, humans do not have the same issues with ketosis that mice do. They don’t get diabetes and they don’t get systemic inflammation. But if you do keto long-term, you may compromise your metabolic flexibility by raising your insulin resistance.

Long-term keto has problems

keto diet and diabetesA lot of people report struggling with carbs when they do strict keto long-term.

That makes a lot of sense. Keeping up insulin pathways when you aren’t eating carbs would be like keeping the lights on when it’s daytime outside — it’s a waste of energy. You aren’t using insulin on keto, so your body probably downregulates your insulin pathways. As a refresher, insulin is a hormone produced by your pancreas that tells your cells to absorb glucose to use as fuel. When you eat carbs, insulin production begins. In the absence of carbs, there’s less need for insulin.

That doesn’t mean keto causes diabetes; it’s amazing for most diabetics. However, if your cells are great at processing fat, but suck at processing glucose or carbohydrates, you won’t be able to run at full power, and parts of your body that prefer glucose over fat — like the glial cells in your brain that handle immune function and synaptic pruning — don’t work as well over time.

Bulletproof Diet is the safe approach to keto

That’s why the Bulletproof Diet uses cyclical nutritional ketosis, and why on days when I eat carbohydrates, I always have Brain Octane Oil so my cells have a steady supply of ketones. This builds metabolic flexibility: you can eat fat and carbs and your body will use them both, which is the goal. You want to be resilient and full of energy no matter what, and that means you want cells strong enough to burn whatever you give them.

Using the Bulletproof Diet, including Brain Octane Oil every day for long periods of time, and eating carbohydrates some of the time but not always, avoiding inflammatory foods, and using Bulletproof Intermittent Fasting, I was able to recently test with perfect insulin sensitivity — I scored a one on a scale of 1 to 120 (see my numbers below). I also had above average glucose tolerance. That’s metabolic flexibility by the numbers!

It’s not a good idea to go on a high-carb, zero-fat diet, and it’s not good to go on a high-fat, zero-carb diet either. Cycling is key, and intermittent fasting is important. “Head Strong,” my book about upgrading your brain, covers carb cycling and intermittent fasting extensively, including techniques that let you do it without hunger.

So don’t worry about a ketogenic diet causing diabetes. It won’t happen in humans according to these studies and my experience. But you will perform better when you use ketosis cyclically and have background ketones present from Brain Octane Oil, which directly raises ketones in the blood even in the presence of carbohydrates. That’s what I do!

So pass the butter.

For more guidance on following a cyclical keto diet, download Bulletproof’s free Keto Recipes for Beginners Cookbook & Cyclical Keto Meal Plan. And while you’re at it, sign up for the Bulletproof newsletter, to get daily hacks on how to upgrade your health and performance.

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