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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