Dear Mark: “High-Fat Diet,” Potential Type 1 Diabetes, Keto Cure?

Dear_Mark_Inline_PhotoFor today’s edition of Dear Mark, I’m answering three questions from readers. First up, what are we to make of a recent study claiming to show that “high-fat diets” are harmful to rodents? Is it truly a high-fat diet, and what does it mean for us? For the second question, I field a comment from a reader experiencing a confluence of troubling symptoms and test results on his keto diet. And third, does keto actually cure diabetes, or just manage it?

Let’s go:

Hi Mark,

My vegan friend sent me a link to this study. She always does when something comes out that seems to contradict Primal. How should I respond?

First of all, I like that you manage to stay friends with her. Sounds like she keeps you on your toes. That’s awesome and commendable.

Second, you don’t have to worry about this study.

It’s a rodent study. Rodents are totally different from humans. They’re nocturnal—their circadian rhythms are flipped. They’re some of the only true granivores—grain-eating animals—which we certainly are not. They can offer insight into mammalian physiology and basic metabolic mechanisms that often apply to us, but they’re not great at showing us how we should eat.

And that “high-fat diet” was actually a “high-fat, high-sugar diet.” This is almost always the case with rodent diets. Unless the study explicitly says “high-fat, low-carb” or “low-carb ketogenic diet” when discussing what rodents were eating, they were probably eating a significant amount of sucrose. It’s standard in rodent chow. Helps them—no surprise here—eat the food.

Right there in the abstract, beyond the headline, you read the truth:

“Adult C57Bl/6 mice were subjected to isocaloric high-fat/high-sucrose diets…”

Most underrated part of that sentence is the “subjected to.” That’s exactly what we’re doing to ourselves—subjecting ourselves to terrible, obesogenic diets.

Anyway, I agree that diets high in both saturated fat and sugar are uniquely bad to eat, and that if you’re going to eat sugar, monounsaturated fat is a better choice. For that reason, the study is helpful. You just have to read past the headline.

From the comment board:

So tell me why my FBG goes 120-140 while ketones measure 6.8 while eating keto. Even on extended fasts of 2-3 weeks. Just doing intermittent fasting and keto i can’t lose anything. In fact i steadily gain. 6’1” 170 endurance athlete frame. Every time ive had my insulin tested its been ridiculously low that there doesnt seem to be a suspension of IR. Ive also had the serum c peptide tested and its also very low.

I hate to say this, but that sounds like it could be Type 1 diabetes. You should see a doctor.

In Type 1, your pancreas isn’t producing insulin. That would explain both the low insulin readings and the high blood sugar, as you’re not making enough insulin to remove glucose from the blood.

Low serum c peptide is another hallmark of Type 1 diabetes.

Ketones levels of 7 are also quite high, although not dangerously so. Given the other biomarkers, though, I’d strongly advise getting checked out.

Also, I’d probably stop doing the three-week fasts and trying to lose weight.

Thoughts on if it’s a functional cure meaning keto must be maintained or if insulin sensitivity can be restored enough to allow eating slightly higher carb?

Great question. I’ll start with the short answer: We don’t know.

Perpetual lifelong ketosis is unnecessary for most people, even most diabetics. Consider how keto improves many of the signs and symptoms of type 2 diabetes.

It reduces pathological insulin resistance by lowering body weight. That doesn’t go away as long as you don’t gain weight.

It keeps both insulin and blood sugar low by reducing the foods that increase them. That only persists if you keep restricting the foods.

However, if you can eat slightly more carbs while maintaining your body weight, that’s a good indicator that you’re not worsening insulin or blood glucose levels. Another good indicator is actually tracking your blood sugar, which I would recommend you do as you increase carbs.

Ultimately, it all depends how you define “cure.”

Can you just stop doing everything that led you to resolution of the symptoms and hope the benefits will “stick”? No.

Can you be entirely sedentary and metabolize glucose like a 15 year-old? No.

No. If you go back to the lifestyle that helped you develop type 2 diabetes, you’ll probably re-develop type 2 diabetes. Maybe it’ll take longer. But there’s no reason to believe the end result will change.

But can you eat slightly more carbs, particularly if you time them with your intense workouts to upregulate insulin sensitivity? Most likely.

Will you be more insulin sensitive just by virtue of having lost all that extra weight? Yes, and it won’t go away as long as you keep the weight off.

This isn’t a cure like antibiotics are a cure for a bacterial infection. You don’t pop a pill, kill the infection, and go back to normal. The cure is ongoing. The therapy never ends.

There’s likely some genetic proclivity happening here—many type 2 diabetics come from a long line of type 2 diabetics. If so, you’re always going to be susceptible. You’ll always have to take those extra steps to keep insulin sensitivity high, whether by making sure to eat your carbs in and around workouts, going keto, religiously optimizing your sleep and circadian rhythm, and doing “everything right.” Don’t pay attention to those people who can get away with eating whatever they want while paying no attention to body weight, exercise, or sleep. That’s just the way life is—rather unfair. They aren’t realistic models for you or anyone else.

Except for those mutants, most people deal with the same issues to varying degrees. Most people can’t eat all the carbs they want without worrying about blood sugar, weight gain, or whether they exercised. Most people should be mindful of the carbohydrates they eat. Type 2 diabetes isn’t an on/off switch. It’s a spectrum.

Thanks for reading, everyone. I’d love to hear from you.

Have you “cured” type 2 diabetes with low-carb or keto? Were you able to incorporate more carbs without problems? If so, how’d you do it?

Take care, be well.

About the Author

Mark Sisson is the founder of Mark’s Daily Apple, godfather to the Primal food and lifestyle movement, and the New York Times bestselling author of The Keto Reset Diet. His latest book is Keto for Life, where he discusses how he combines the keto diet with a Primal lifestyle for optimal health and longevity. Mark is the author of numerous other books as well, including The Primal Blueprint, which was credited with turbocharging the growth of the primal/paleo movement back in 2009. After spending three decades researching and educating folks on why food is the key component to achieving and maintaining optimal wellness, Mark launched Primal Kitchen, a real-food company that creates Primal/paleo, keto, and Whole30-friendly kitchen staples.

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26 thoughts on “Dear Mark: “High-Fat Diet,” Potential Type 1 Diabetes, Keto Cure?”

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  1. “if you’re going to eat sugar, monounsaturated fat is a better choice” – so, why would saturated fat be worse to eat than monounsaturated fat? Saturated fat is marginally more stable / less subject to oxidation than monounsaturated fat, right?

    I’ve always assumed that the favorable press in favor of monounsaturated fat is the result of anti-meat/anti-saturated fat/pro-plant bias among nutrition scientists and nutrition journal editors, affecting both what is investigated and what is publishable. Has anyone actually done a controlled head-to-head of saturated fat + sugar vs. monounsaturated fat + sugar and determined that monounsaturated is better, and given a credible biochemical explanation of why? Or is there something else that I’m missing?

    I can’t think of any reason why monounsaturated fat + sugar should be any less harmful.

    1. If you take the time to dig around on the archives here you should find your answer in an article on carb re-feeding. As I recall, the recommendation is to limit sat fat to 50g when the carbs go beyond a certain threshold which I don’t recall.

    2. Go to Pubmed and you’ll see studies that show insulin response is increased by saturated fat but not so with monosaturated fat such as olive oil. So I think Mark’s point is if you’re a sugar junkie better to lean towards a higher ratio of monosaturated fats to saturated fats. However, if you are on a low carb diet and your blood sugar is under control, then you can enjoy the benefits of saturated and monosaturated fats and decrease that ratio. It’s a non issue IMHO if you consistently adhere to a Primal or a keto diet.

    3. Saturated fat that is poorly metabolized — neither efficiently stored nor used for fuel — impairs glucose clearance:

      So spiking blood glucose with carbs while dumping a large amount of saturated fat into the bloodstream worsens insulin resistance.

      Monounsaturated fat, however, improves fat metabolism, through improved cell membrane permeability and circulatory efficiency inter alia, producing an insulin-sensitizing effect:

      This is, of course, largely academic as the sane choice is to avoid chronic glucose overload in the first place.

      1. The second abstract is exactly what I’m concerned about – it reads like a grab-bag of bad science. That’s why I was curious whether there was a controlled intervention that compared sat fat + sugar to monounsatured fat + sugar – but what I’m seeing looks nothing like that, just dubious “scientific conventional wisdom” that is largely grounded in epidemiology.

  2. Hi.

    Interesting info about how safe it is to go back to eating some carbs. I spent about 3 years mostly in ketosis through diet. I think it may have really harmed my health. My fasting blood glucose was 93 for a few years, not high but not as low as my usual norm of 79-80. I finally got enough information to realize that high fat/low carb eating is not the way for me to go. My fasting insulin was high as well as other markers being “off”. I didn’t lose weight either, instead gaining slowly but steadily. These days I eat almost no fat of any kind. Feeling much better, back down to high school weight, fasting blood sugar back down to normal. I focus on plenty of complex carbs, not too much grain and NO processed or refined “food like products”. I think I may be one of those insulin sensitive types, even though being somewhat overweight much of my life. I have even been able to start exercising again after a few years of being just too tired and depleted to do anything. Some of us just do better on low/non-fat. high complex carb, or vegan type diets. There is nothing that says we are all “meant” to eat only a certain way. After many years of researching, doing experiments of 1, and watching all my numbers, I just think there is no one diet that fits all. This has caused a lot of unnecessary confusion for a lot of people. Americans simply eat too much of the wrong things, and sadly, many of us don’t have any good choices (think of “food desert” type places). It is a shame that in a country so rich in every way, that not all of us have access to food or information that would help to get us out of this health crisis.

    Thanks again, Mark for all you do.

    1. When you were in ketosis, were you under-eating? What were your macros? What was a typical meal? What was a weekly meal plan? Was your fat high? What were your sources of fat?

      The Primal Blueprint is pretty detailed. I’d love to see if what you did really was on the BP or whether you were more on the ‘lean and clean’ pathway. ‘Lean and clean’ is neither the BP, nor what Mark recommends for Keto.

      Im sincerely curious, not trolling. Please give us more information otherwise the post raises more questions than answers.

    2. Would also be interested to know if you tested your thyroid function.

    3. I am curious – what did you eat while on your ketogenic diet?

  3. Great post! Studies like that mouse study drive me nuts. It’s so easy to misinterpret things. And I just try to be respectful of the health choices of my friends…I don’t share info unless they ask me. But lately everyone is asking!

  4. Interestingly, there is a line of thought re: curing type 2 diabetes – the rationale is that it’s necessarily to rapidly de-fatty the pancreas to help return it to normal function: – it seems to work best with those who have been diagnosed within 10 years.

    I guess you have two options: a) Stick yourself through an ultra-low calorie diet for 8-10 weeks as per above study, and then try to behave yourself after, or b) switch to a low carb, high fat diet and at least have a more enjoyable existence whilst controlling T2D.

    1. Id like to see a post about the difference between "managing" and "curing" type 2 diabetes. My sense is that the allopathic medical establishment resists talking about a cure for non-medical reasons. What I dont get is why? The idea of a cure is so much more empowering than management. Theres a mystery here I dont understand.

      1. I think it’s more than that. To some extent, curing and excellent management result in the same thing: control of the initial problem. What is interesting, that some people, who know exactly what they need to do for, say T2D, to be medicine-free, won’t do it because it’s too much effort on their part. If someone’s not going to stick to a ‘relatively’ easy life of a low carb, high fat diet to completely manage their condition, what hope do they have to sticking to 800 cals a day for half a year?

        And to some extent I can sympathise. To quote a Blur album title, modern life is indeed rubbish at times.

      2. My understanding is that beta cell function wanes after diagnosis of T2DM, especially if it’s been more than 10 years. In essence, insulin resistance is so high that the insulin-producing beta cells “burn out”. Keto introduced later in the game can definitely increase your insulin sensitivity, but the success of removing medications relies on how much insulin the person is capable of producing. At any rate, decreasing the insulin demand is beneficial for overall health and prevention of cardiac/renal/peripheral issues.

  5. Longtime T1 diabetic here. Untreated T1D leads to dramatic weight loss, not gain. (Mark, you’re great at many things, but please follow your own guidelines and don’t attempt individual diagnoses, especially of such a huge, life-changing condition.) LADA *might* be a possibility … but, as you suggest, a visit to the doc is probably in order.

    1. Mark did say “could be” and recommended seeing doctor. I feel that this is good practice. If someone comes with a bunch of symptoms, it would be negligent not to do this. He was not diagnosing, simply voicing his concern in response to the question. Better this and risk being a bit scary than keeping quiet in case poster finds it hard to handle.

      1. However, the fact that Mark was mistaken in his interpretation of one of the major symptoms of Type 1 diabetes (weight loss vs. weight gain) points to a significant problem with his post. There is already a great deal of misinformation about Type 1 diabetes in the media, as well as dangerous conflating of the disease with Type 2. Mark’s post could theoretically dissuade a reader with undiagnosed T1D from seeing the doctor.

        People pay attention to what Mark Sisson writes — with good reason, I believe — but he is not a physician and should restrict himself to advising readers whose symptoms are worrying to seek medical help.

        1. I have a type 1 diabetic friend I’ve known for years. She had always har a problem with her weight. Overweight. She also doesn’t eat SAD anymore. She does watch what she eats and tries to eat someone primal.

          But she still has trouble losing weight. The body is more complex than T1D = weight loss. Or w ight gain.

          Thyroid plays a part. So do
          Many other games hormonea ane functions we aren’t close to understanding.

          So, I agree with your comment that Mark may be off with his “diagnosis.” But so might you be. Just because you’re living as a type 1 with weight issues, doesn’t mean it applies to everyone. I’ve seen the opposite with my own eyes. So clearly more is going on here.

          1. I hate that there’s no edit function. Excuse my spelling. Phone typing is not fun…

          2. *Untreated* T1D leads to weight loss- was what I said. Once someone is on insulin, then a variety of weight issues can exist.

          3. Where in my post did I say I was living with weight issues? You’ve misread. What I pointed out was that *untreated* Type 1 diabetes causes weight loss — i.e. someone who has not yet been diagnosed and is not yet taking exogenous insulin is unable to metabolize carbohydrate and will lose weight (and eventually die, if insulin therapy is not initiated). Once insulin therapy has commenced, a person with T1D could be overweight, underweight, or anything in between.

  6. A chronically elevated FBG in the 130s-140s is probably due to a combination of problems, but it also suggests that a ketogenic diet is not the right choice for you. Not everyone can tolerate every diet. DM2 is a polygenetic cluster of diseases and manifests itself differently in different people. DM1 seems unlikely as it would probably be accompanied by weight loss.

    The body is conservative. If you aren’t using a metabolic pathway, your body is going to downregulate production of those enzymes which would account for the low insulin/C peptide production. Why waste energy manufacturing something that you don’t use? Since insulin is an anabolic hormone, you may notice poor muscle mass over time as well.

    Additionally, there is a growing body of evidence that suggests both saturated fats and branched chain amino acids contribute to insulin resistance. Since protein and saturated fats are frequently used in place of carbohydrates, it’s likely that this is contributing to your increased insulin resistance.

    Discuss the problem with your doctor to rule out other issues. Since your weight is not under control and your biomarkers are poor, it’s probably time to consider some other dietary approach. One other commenter here suggested a Newcastle type diet for a few months. You could follow that with a Greek type diet that gets a lot of energy from olive oil, if you still want to avoid carbs. Either way, you’ll probably need to count calories to get the weight under control, but good weight control is the real secret to DM2 control. With a calorie counting app, calorie counting is no more difficult than carbohydrate counting.

  7. I’m curious about the reduced beta cell function in Type 2 Diabetes. As far as I know, people who have developed Type 2 Diabetes can decrease their insulin resistance but will often remain insulin deficient (of varying degrees based on individual pathophysiology, years with the disease, and medications used). I hesitate to use the word “cure” because even if you go Keto and your insulin sensitivity is that of a child, you likely can’t tolerate high glycemic foods if you’ve lived with the disease for longer than five years.

  8. I lowered my a1c from a 13 to a 4.6 in 2017 with Keto and hiking. I went off Keto and increased my carb intake a bit in December and my a1c shot up to a 7. So I will be sticking with Keto and exercise for the rest of my life. I’m down 109 pounds with a goal of losing 30 more pounds.