The Pros and Cons of Long-Term Keto

Personally, I do best on a keto diet. When I’m eating at the lower-carb side of things, I feel smoother, clearer, and more alert. I don’t suffer blood sugar crashes (hanger!) and I generally motor along pretty well for a late middle-aged, has-been athlete.

I’ve been on a low-carb regimen for 22 years now. Yep, more than two decades! I’ve tinkered with things like “safe starches” and slow carbs, but I’ve always felt best at the low carb/keto end of the macro spectrum.

My specific problems with consuming too many carbs are poor blood sugar control and some gut issues. Not everyone has either of these problems, but when you talk to folks who have eaten a low-carb diet for more than a few months, they usually report feeling better, improved digestion, and improved blood sugar control.

But my fondness for keto doesn’t mean I recommend it for all people, all the time. No—I view ketosis as a multi-purpose tool. Effective for a variety of jobs, but not the default diet for every person under every circumstance.

There are some exceptions, I think. Long-term ketosis may well be helpful for treating diabetes, mitigating the risks of certain cancers, and treating or preventing various neurodegenerative diseases. But, in general, I view ketosis as a tool to use only so long as it’s working for you.

One should be flexible rather than dogmatic about this topic. After all, I’ve seen keto break enough folks over the years. While it’s great for me and many others, we’d do well to not turn its use into the nutritional equivalent of a cult.

Why not stay in ketosis all the time? Before I dive into the details, the short answer is: For some, this is fine or even optimal. For others, a seasonal “toe dip” into ketosis works wonders. Yet, still there are other people who find keto to be a metabolic “no-fly-zone.”

Let’s first take a look at what ketosis is, what we know about it, and the long-term pros and cons. Then, you can use that information to decide whether or not keto is a good fit for you, specifically over the long-term. Ready to dive in?

What Is Ketosis?

When carbs are available, your brain and body will use them. Instead of burning body fat at rest, you’ll burn glucose. We just condensed a whole textbook of metabolism into one sentence! Lots of details here, but for our purposes, this is accurate enough.

Burning sugar for fuel is the default state cultivated by the modern Western diet, and it’s not a great place to linger in. When someone continually pounds refined foods, they will inevitably over-eat. As a consequence, their blood sugar and insulin levels stay chronically elevated. This metabolic dysregulation, in turn, starts the downwards spiral that leads to type 2 diabetes and a host of other metabolic driven diseases.

That’s what happens when refined foods, typically built around simple carbs, are abundant. But what happens when you remove the carbs, or trade in your potato chips for broccoli?

Blood sugar falls, insulin levels fall, and your liver starts burning fat and producing ketones. In other words, you enter a state of ketosis.

Our knuckle-dragging forebears were frequently in ketosis. They didn’t always have access to carbohydrates, nor a consistent eating schedule. Ketones provided much needed brain fuel when glucose was scarce.

These days, ketosis is less about survival and more about health improvement. Both the keto diet and fasting (the two main ways to enter ketosis) are used for a variety of therapeutic purposes, most notably weight loss.

I’ve been saying it for years: sustainable weight loss isn’t just a game of calories in, calories out. The state of your metabolism matters. Your hunger hormones matter. Nutrient density matters.

A ketogenic diet can get these areas moving in the right direction, and quickly, too.

Therapeutic Applications of Nutritional Ketosis

The ketogenic diet was originally developed in the 1920s to treat childhood epilepsy. Researchers noticed that, at higher ketone levels, children would have fewer and milder seizures.

Since then, entering ketosis through diet (aka, nutritional ketosis) shows promise in many other facets of health. I’ll review the top four now.

#1: Weight loss

Keto is best known as a weight loss diet. And while it’s not the only diet that works for this purpose, it’s certainly an effective one.

There are dozens of keto weight loss studies to choose from, but I like to cite a 2003 randomized controlled trial from the Journal of Clinical Endocrinology and Metabolism. In the study, obese women lost more weight on a ketogenic diet than controls lost on a calorie-restricted low fat diet.

Here’s the interesting part. Even though they weren’t told to limit calories, the keto women STILL cut calories in line with the calorie-restricted group.

This makes sense when you understand that a keto diet suppresses hunger hormones like ghrelin and neuropeptide Y. Less hunger, less overeating, less weight gain.

#2: Diabetes

I’m baffled—flabbergasted, even—that the ketogenic diet isn’t standard of care for type 2 diabetes. The writing is on the wall, people!

For instance, a recent consensus report in the journal Diabetes Care pegged low-carb diets as the intervention with the “most evidence” for combating high blood sugar. This claim is supported by the Virta Health study, a year-long intervention in which a supervised keto diet was shown to reverse diabetes (as measured by HbA1c) for the majority of 218 type 2 diabetics.

#3: Neurodegeneration

As we age, our brains get worse at using glucose. This contributes to cognitive decline, and may drive certain flavors of Alzheimer’s disease.

The aging process, however, doesn’t seem to affect ketone utilization, which is one reason why researchers are excited about ketosis for dementia prevention and mitigation. Supplementing with MCT oil (a highly ketogenic fat) seems especially promising.

#4: Cancer

In the 1920s, Otto Warburg discovered that cancer cells run primarily on glucose. This finding, now dubbed “The Warburg Effect”, has seen a resurgence lately as researchers explore metabolic therapies (like ketosis) for cancer.

Cancer cells love high blood sugar and insulin levels, and the keto diet minimizes both biomarkers. Bad news for cancer, good news for people.

Stay tuned on this one. Lots of research is underway.

The Data on Long-Term Keto

Keto is one of the most studied diets on the planet, but don’t expect any 5 or 10 year keto vs. Mediterranean diet trials anytime soon. It’s super expensive and super challenging to do nutrition research for that length of time. It isn’t likely that we’ll get to see these long-term studies.

What about epidemiology? Well, we have the traditional Inuit, who lived in fairly good health on diets full of blubber and free of carbs.

But the Inuit, researchers speculate, have genetic adaptations to help them process fat more efficiently. Long-term keto for the Inuit? Not the same as long-term keto for the general population.

And so, whether or not keto is the “best” long-term diet for you depends on your unique physiology and therapeutic goals. And permanent ketosis is not without risk.

Long-Term Keto: Potential Risks

I’m not against ketosis. Definitely not. For people like me, it might be the ideal state.

But it’s important to keep an eye on potential downsides. To my eye, the main problem areas tend to be:

  • LDL-P. A subset of folks see a large spike in LDL particle number (LDL-P) after going keto. Since high LDL-P (also tracked by a marker called ApoB) is correlated with increased heart disease risk, this is worrisome. We don’t know for sure if rising LDL-P is bad news for keto folks specifically, but I believe it’s better to be safe than sorry. That’s why I recommend these “hyper-responders” bump up carbs. More on that soon.
  • High-intensity exercise. Many elite athletes thrive on a keto diet, but some don’t. Why not? Because high-intensity activities like Crossfit, HIIT, or obstacle races require extra glucose for energy. Again, adding back carbs is usually the answer here.
  • Gut health. A keto diet tends to be low in soluble fiber, the type of fiber your gut’s bacteria like to munch on. In the case of SIBO (small intestinal bacterial overgrowth), this is probably a good thing. Keto starves the bad bugs. But for most folks, a long-term lack of fiber could be selling your gut short. For instance, when your gut bacteria ferment soluble fiber, they create compounds like butyrate that reduce inflammation and strengthen the gut barrier. All that said, it appears the amino acids in protein can also play a role in the production of the short chain fats that feed the gut, just like fiber from plants! Now, this does NOT mean that keto and carnivore are the best option for everyone, everywhere—but it does make it pretty tough to claim that keto is inherently bad for gut health.

How To Bring Back Carbs

In my book, Wired to Eat, I lay out what I believe to be the optimal long-term diet (for folks that fit the mold, so-to-speak). For the detailed explanation you’ll have to read the book. But, to simplify and summarize: it’s basically a mix of healthy fats, plenty of protein, and 50-150 grams of paleo-friendly carbs per day.

If you’re used to eating keto and want to ease back into carbs, you're probably wondering how to do it, and with what kinds of foods. I recommend testing the waters before diving in head-on.

First, grab a blood glucose monitor. Then, eat 25-50 grams of healthy carbs—your choice of sweet potatoes, fruit, legumes, white rice, or another—in one sitting. Last, check the change in your blood glucose levels. Repeat with a different carb source. You’re looking for the food that resulted in the smallest blood sugar impact 1 or 2 hours post-meal.

Your gut should also guide you. Rice makes me feel like a clown is inflating balloons in my intestines, but berries sit fine. This may take some experimenting. Don’t give up after one gassy failure.

Ketosis Is A Tool

Is keto the best long-term diet? Honestly, nobody knows.

We’re far too variable of a species to make broad-ranging claims like that. And most humans throughout the course of history weren’t in ketosis permanently. They cycled in and out.

My money is on the cyclical approach. Enter ketosis for the health benefits when it is timely, then have some carbs to refuel glycogen tanks, feed gut flora, and upregulate LDL particle clearance.

And as always, never stop carefully monitoring your body: how you look, feel, and perform. It’s a healthy way to be in the world. Stay wired (and salty), everyone!