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Ketogenic Diet 101: Exogenous Ketones, The Fat Adapted Diet, and More About Keto

Listen to Dr. Neal address this topic on Episodes 135, 290, 430, and 605 of the podcast Optimal Health Daily.

Imagine it’s 2012. Picture me walking around a busy downtown street stopping people at random and asking them if they have ever heard of the Ketogenic diet. I would guess that fewer than 10 people would have responded in the affirmative, even though the diet has been used since the early 1900s to treat epilepsy. Fast forward to today and I am willing to bet that 25 or more would know something about the Ketogenic diet; it’s being used to help treat a number of health conditions. But that doesn’t guarantee effectiveness.

Is the Keto Diet effective at all? If not, then, why the sudden jump in popularity?

Part of the Ketogenic diet’s recent popularity isn’t necessarily because it is effective for the treatment of health conditions or that it’s useful for weight loss in the long term. Instead, we can attribute much of its popularity to athlete and celebrity endorsements. A handful of world record-setting endurance athletes swear by the Ketogenic diet and insist that it played a large role in their athletic achievements.

What’s So Special About the Ketogenic Eating Pattern?

Typical American diets consist of about:

  • 60% of one’s daily energy (i.e., calories) coming from carbohydrates
  • 15% from protein
  • and 25% from fat

Contrast this with the Ketogenic diet which requires:

  • 10% of one’s daily calories from carbohydrate
  • 20% from protein
  • and a whopping 70% from fat

Essentially, it’s a lower carbohydrate, high-fat diet. It’s called a Ketogenic diet because this lowered consumption of dietary carbohydrate leads to the build of things called “ketones” in the body.

What Are Ketones?

You all are familiar with one type of ketone: nail polish remover (aka acetone). Acetone is just one type of ketone, and yes, when our bodies are in a state of “ketosis,” meaning the body is creating ketones, one of the ones produced is acetone. If you were to follow this diet over a period of 2 weeks or longer, you would be in a state of ketosis – meaning your blood levels of ketones have increased to a higher than normal level. Now you’re probably thinking…

Is being in a constant state of ketosis bad? Is it possible that following such an extreme diet could be beneficial?

Studies on the Keto Diet

Based on observational case studies performed in the 1920s, explorers observed Inuit populations consuming large amounts of dietary fat and not a whole lot of carbohydrates. At the same time, they did not appear to suffer from the chronic diseases commonly seen in Western societies. But here’s something we’re learning: those with Inuit ancestry may have a special genetic adaptation that helps them thrive on a ketogenic diet–a genetic adaptation that the rest of us don’t have. This adaptation prevents their bodies from producing ketones!

But since then, studies have been performed to test the effects of the Ketogenic diet. The majority of these studies have recruited elite athletes as participants. Results showed that, during activity, these athletes burned more fat as fuel and were able to improve their endurance. It is often assumed that the ketones are what help this extra fat burn.

We know that in the short-term, when otherwise healthy individuals follow this eating style, it appears to be relatively safe. But when switching from a standard American diet, which consists mostly of carbohydrates, to one of mostly fat, there will be some side effects. Individuals often complain of:

  • feeling fatigued (which could be the result of having low blood sugar due to the decreased intake of carbohydrate)
  • constipation (also due to the reduced carbohydrate intake)
  • diarrhea (because of the increased fat intake)
  • gallstones
  • vitamin deficiencies

Are Exogenous Ketones Safe and Beneficial?

For those that aren’t aware, you can buy exogenous ketones from supplement manufacturers. What if you were to avoid following this strict diet altogether and just ingested ketones from a bottle? Would that provide the same effect? Sadly, we don’t know at this time. Why? There are a number of reasons.

One reason is that, often, supplement manufacturers will add other ingredients to their supplements. You may think you’re purchasing ketones, but you’re getting ketones with other ingredients like:

Because of this, we don’t know whether it’s the ketones that may help burn fat, those other ingredients, or a combination of the two. Also, there simply aren’t enough studies. We have some studies examining the use of raspberry ketones, but not other forms.

Can the Keto Diet Prevent & Cure Cancer or Autism?

Let’s talk about cancer patients and the Ketogenic diet. There are a few small studies that examined this very question. The theory is that since cancer cells love carbohydrates, by severely restricting carbohydrates, you might be able to kill the cancer cells by starving them. Some very small studies have been conducted–like under 20 patients. One study started with 16 patients, but by the end, only had 5 left. Here’s what happened, I will quote the study’s authors:

“One patient did not tolerate the diet and dropped out within 3 days. Among those who tolerated the diet, two patients died early, one stopped after 2 weeks due to personal reasons, one felt unable to stick to the diet after 4 weeks, one stopped after 6 and two stopped after 7 and 8 weeks due to progress of the disease, one had to discontinue after 6 weeks to resume chemotherapy, and five completed the 3 month intervention period.”

So even though this study only lasted 3 months, some found it challenging to follow the diet within this short time frame. Plus, it becomes really difficult to make health recommendations when so few are in the study sample.

Moving on to ADHD and autism: the majority of the studies examining the Ketogenic diet on these conditions were performed in lab animals like mice, rats, and dogs. One small study was conducted back in 2003 and found improvements in the behavior of autistic children when they followed a Ketogenic diet. The problem is that about 23% of the children dropped out because they couldn’t stand the diet.

How Does the Fat Adapted Diet Compare to the Keto Diet?

In general, the Fat Adapted diet (aka Fat Adapted program) is similar in many ways to the Ketogenic diet. The goals are also fairly similar: help the body burn more fat as fuel more often. The Fat Adapted diet is basically a keto-type diet for athletes. Since body fat is in great supply, the theory is that if we can use fat as our source of fuel during exercise, we may be able to maximize our performance. The hope is the body will adapt to burning more fat more often–hence the name “fat adapted” diet.

Depending on the version followed, the macronutrient breakdown for the Fat Adapted diet would look something like this:

  • about 65% of daily calories should come from foods that are high in fat
  • about 25% of the calories for the day is supposed to come from carbohydrate-rich foods
  • and 10% from protein

The hope is that by doing this, the body will change its metabolism and turn to burning fat as fuel more often.

More on the Ketogenic Diet and Ketosis in the Long Term

I should also mention that because many of the more recent studies examining the health effects of the Ketogenic diet used elite athletes as participants, this is a very unique subset of individuals. Elite athletes have very different nutritional needs when compared to those of us that do not possess these superhuman-like abilities. Further, even those that are active on a regular basis are already changing their metabolisms. The higher your level of cardiovascular and muscular fitness, the more likely you are to burn fat ALL the time, independent of what you eat!

Also, as mentioned above, the majority of the studies were performed over the short-term (<6 months). I recently attended an academic conference and happened to speak with one of the leading Ketogenic diet researchers Marlia Braun, PhD, RDN and asked, “We have all of this data on the short-term effects of following a Ketogenic diet, but what happens when otherwise healthy individuals follow this diet for a year or more?”

Her response: “We don’t know.

It is possible that over the long-term, individuals may not experience these same benefits. Plus this diet is very strict. I am not so sure that long-term adherence is realistic for most folks.

If this type of eating pattern appeals to you, it would be wise to discuss the Ketogenic diet with your physician to be sure that it is safe given your current health status and prior health history. I would also recommend that you incorporate this pattern of eating very slowly to prevent any uncomfortable side effects.

All Low Carb Diets: A Summary

In a nutshell, lower-carbohydrate diets appear to be safe for most people in the long-term. And, if you’ve read or listened to me before, you know there’s a “but” in there somewhere… and you’d be right. Notice I said “lower” carbohydrate diets instead of “low-carbohydrate” diets. I have to mention something right off the bat: there are different definitions of what a “low-carbohydrate diet” really means.

If you follow the Atkins Diet for example, for the first 2 weeks you’re only eating about 20 grams of carbohydrate each day, mostly from vegetables. To put this in perspective, 1 slice of bread contains about 13 grams of carbohydrate, so you’d be pretty close to your max for the day right there.

The South Beach Diet recommends that folks consume no more than 120-140 grams of carbohydrate per day. Again for perspective, adults living in the U.S. and do not follow a low-carbohydrate diet, we consume on average about 350-400 grams of carbohydrate each day.

And of course, there’s the Ketogenic diet that we’ve just discussed.


Most studies follow people on these diets for one year max. This means we don’t know what may happen if they were to continue following these diets for more than a year. Would we see their weight come back? Would their cholesterol levels suffer? At this time, we really don’t know. You may be wondering, “Well, why don’t we study people for longer… then, we’d have our answer!” Those types of long-term studies are very expensive. Also, it’s very difficult to get people to commit to a long-term diet study. Why? Because most folks can’t follow the prescribed diet for more than 6 months, let alone more than a year! In fact, when I conducted my research, we had a 50% dropout rate when that 1 year anniversary came around: we started with 180 people in our study and ended up with only 90 by the end.


In my experience… I want to repeat that: in my experience (which means this not based on formal research), I have found the sweet spot for people, especially those that want to lose or maintain their weight is to consume about 50% of their calories from carbohydrate each day. That’s about 250 grams of carbohydrate per day. This means you could eat a cup of oatmeal in the morning, a sandwich with 2 slices of bread for lunch, and 1 cup of cooked pasta for dinner…throw in 2 servings of fruit and 5 servings of low-carbohydrate vegetables each day (like green leafy veggies, tomatoes, broccoli, mushrooms, and so on) and you’d basically be at 250 grams of carbohydrate right there.

Sound reasonable? That’s because this is really about watching those carbohydrate portions to help yourself consume less as opposed to following a specific low-carbohydrate diet. And because this diet isn’t as extreme, it’s usually easier for people to follow as a long-term change.

For people with type 2 diabetes following a low-carbohydrate diet: this does happen, but usually it’s a lower carbohydrate diet as opposed to following Atkins, South Beach, or the Ketogenic diet. Those with type 2 diabetes may want to follow a lower carbohydrate diet because having diabetes prevents the body from being able to process carbohydrates properly. So by eating less carbs, the body is happy.


Are there any health risks associated with following a low-carbohydrate diet over the long-term? Again, we don’t know for sure, but a list of the typical side effects based on the research that has been conducted are:

  • fatigue
  • weakness
  • constipation
  • kidney stones and other kidney problems
  • bad breath

The bottom line is that for most folks, following a lower-carbohydrate diet is likely safe in the long-term but notice again, I said a “lower” carbohydrate diet. Going on a very low carbohydrate may be a different story.

Listen to Dr. Neal address this topic on Episodes 135, 290, 430, and 605 of the podcast Optimal Health Daily.