These days, I can’t give a seminar, or host a Facebook live session without someone asking me about the Keto diet. And I get this question all around, from the corporate folks that I lecture, to my talks at the naturopathic college, and personal training conferences. Everyone wants to know about the Keto diet.

            It’s very polarizing, and at the one end of the spectrum, proponents will claim that it enhances performance (mental and physical), makes the pounds fly right off, and even saves you money on your car insurance. The detractors from the keto diet will have you believe that it clogs up the arteries, and could lead to a coma.

            So what’s the truth? The truth is usually somewhere in the middle. And while some people use the keto diet for neurological conditions (like epilepsy, Alzheimer’s, Parkinson’s, etc.), since I’m a personal trainer, I’ll focus on what I know – fat loss, and athletic performance.

            In this article, we’ll discuss:

• What is the keto diet?
• Is the keto diet safe?
• Is keto healthy long term?
• Keto and weight loss
• Keto and diabetes
• Keto and athletic performance
• Can you eat more calories on keto and still lose weight?
• Adherence to the ketogenic diet
• Why the keto diet is so popular

If you’re prefer to watch a video of this information, rather than read the article, here it is:

What is the Keto Diet?

            The keto diet (full name: ketogenic) is a low-carb, low-protein, high fat diet. Unlike most low carb diets, which advocate high protein, this one is low carb and low protein.

            For my “numbers” people, a typical low carb diet might be 40% protein, 40-50% fat, and 10-20% carbs. A keto diet might look like this: 20% protein, 75% fat, and about 5% carbs.

            The most common foods for keto people would be things like butter, bacon, eggs, olive oil and avocado. The few carbs that they do get come from non-starchy vegetables, like spinach, broccoli, asparagus, etc.

            It’s not at all a new diet. It’s just trendy now, because the world of fitness and nutrition goes in 30-year cycles. What’s popular now was previously popular in the 1980s. What was popular in the 1980s was previously popular in the 1950s, etc. And the same goes for the keto diet, which was first “invented” in the 1920s as a method to treat epilepsy.

            But let’s backtrack: what does the word “ketogenic” mean? It means that it’s a ketone-producing diet. Now that’s not very helpful, is it? Now we have to define what “ketones” are. So here’s that definition: a ketone is a chemical made by the liver when your primary fuel source (glucose AKA sugar) is depleted. So it’s an alternate fuel source.

            Why would we want to use an alternate fuel source? Because the theory goes “we have 2 fuel sources we burn to stay alive: sugar (glucose) and fat.” So if we take away 1 fuel source, we’re only left with one other fuel source to burn. Take away sugar, and you’re only left with fat to burn. So people think that if they remove carbs, they’ll burn fat. And that’s true. But we need to distinguish between dietary fat and body fat.

            What determines whether you’ll burn body fat or dietary fat on the keto diet is the total number of calories that you’re eating. If you’re consuming more calories than you need to maintain your weight, you’ll burn dietary fat. If you’re consuming less calories than you need to maintain your weight, you’ll burn body fat. So as I outline in my article on the (un)surprising truth about why we get fat, the biggest determinant of body fat is good ol’ calories. Not the ratio of carbs to fats.

            Now that we know what the keto diet is, let’s talk about…

Is the Keto Diet Safe?

            The question of safety depends less on the diet and more on the person doing the diet. Additionally, it also depends on the duration of the diet.

            One of my most popular presentations that I do for corporations is called “Healthy Foods that Poison: Why You’re Getting Sicker and Fatter Despite Eating Healthier.” In that presentation, I say “there’s no such thing as a good or bad food. There’s only the right food, for the right person, at the right time.” The same goes for overall diets. The keto diet has its place.

            Although not much scientific research exists on the long-term use (beyond 1 year) of the keto diet, in the short term, it does appear to be safe for the majority of people. Is it effective? Yeah. Is it the most effective diet that ever was created? No. The keto diet is an option. It’s not the only option.

            However, there are certain cases when the keto diet should be avoided, like:

• If you have hypothyroidism (a slow thyroid). Low carbs tend to suppress thyroid function in a couple of ways (this is going to get technical). They decrease the total amount of thyroid hormone produced (T3 and T4), and they increase the amount of reverse T3 (a molecule very similar to the active T3, but without the same function, so it blocks real T3 from exerting its effects)
• If you have gout. It’s caused by a buildup of uric acid in the blood, which comes from a high consumption of purines. Purines are found in generally keto foods, like bacon, some fish (like sardines, anchovies, herring, etc.)
• If you have had your gallbladder removed. When the gallbladder is removed, people have a hard time digesting dietary fat. And the keto diet is a very fat-based diet.
• If you have menstrual disorders. Difficult periods, skipped periods, etc. Extremes in carbohydrate/fat ratios may modify the estrogen:progesterone ratio. Sometimes it’s in a favourable way, and sometimes it isn’t, depending on what the ratio was to begin with.
• If you’re trying to build muscle. The low amount of protein on a keto diet is definitely not the diet for you if muscle gain is your primary goal.
• If you’re an athlete, and value your performance. I’ll talk about this one later in this article.
• If you have osteoporosis. Although the keto diet has not been directly studied in people with osteoporosis (to my knowledge), children who are put on a keto diet for several years (for their epilepsy) show smaller increases in bone density compared to kids not on a keto diet. Which makes sense. For the most part, two of the most necessary nutrients for bone growth are protein (bones are made of protein) and calcium. Since the keto diet is a low-protein diet, and the richest sources of calcium are sardines and dairy, those nutrients may be lower in someone following a keto diet.
• If you like pizza. Just checking that you’re paying attention.

Outside of these cases, the keto diet does seem to be quite beneficial for a number of things like:

• Weight loss (but again, no better and no worse than other diets of equal calories)
• Improved blood sugar
• Better hormonal profile for women with PCOS (if you want, you can read more about PCOS in my article on how to lose weight with PCOS)
• Improved blood pressure

Is Keto Healthy Long Term?

            Unfortunately, very little research exists on the long-term use of the keto diet. The long-term research that does exist primarily exists in epileptic children, and mice. And unfortunately, you can’t generalize from epileptic children and mice to the rest of the population.

            As it stands right now, the answer to “is keto healthy long term?” is a big “we don’t know.”

            The longest studies in humans without epilepsy are right around a year (give or take a few weeks). Over a 1-year time frame, there appear to be no negative health consequences.

            But the real warning isn’t about safety. More about effectiveness, and this applies to every diet, not just keto. Think about the mentality of dieting. It’s inherent right in the language. We say that we’re going “on” a diet. Does that imply that at some point, we’ll go “off” the diet?

            As you know, adherence to diets in the long term is VERY bad (we’ll address this at the end of this article). Very. If you think you can do keto long-term, give it a shot. If not, it’s better not to start to begin with, because yo-yo dieting is more damaging to your health than keeping a stable weight, even if that weight is above your ideal.

The Keto Diet for Weight Loss

            The vast majority of people who go on the keto diet do so for weight loss, so let’s address that one.

            The question isn’t really “can you lose weight on a keto diet?” Of course the answer is yes, if the calories are low enough. I think that the question really should be “is it easier to eat less on a keto diet compared to a different diet?” Why is that the question to ask? Because most people don’t count calories, and the ones that do, don’t do so long term. Most people (myself included) go by feel. You feel full, you stop eating. You don’t feel full, you keep eating. So without counting calories, do you feel fuller on fewer calories on a keto diet, vs. a different diet?

            The answer, from emerging evidence appears to be “yes!”

            In one study, 89 obese diabetics were divided into 2 groups:

• Group 1: keto diet group
• Group 2: same number of calories as group 1, but higher carbohydrates

At the end of this study, the keto group lost more weight, and more off their waist compared to group 2.

Another large meta analysis (a study of several studies) found the same thing: a keto diet is easier to maintain long term than a low fat/high carb diet.

However, there are still a number of unanswered questions about the ketogenic diet. The biggest one is how does a keto diet compare to a typical low carb diet? After all, let’s remember that a typical keto diet is low carbs, and low protein. A typical low carb diet is low carb, but high protein. That research exists for epilepsy, but to my knowledge, not for weight loss, which is what we’re dealing with in this article.

Can the Keto Diet Help with Diabetes?

            According to the research, the answer is a resounding “yes.” In one study, researchers recruited 363 overweight and obese diabetics, and divided them into 2 groups:

• Group 1: keto diet
• Group 2: low calorie diet, but more of those calories came from carbs, compared to group 1.

The results: both groups improved, but group 1 had superior results compared to group 2.

            Now, in this study, a low-calorie keto diet was compared to low-calorie, non-keto diet. But what happens when a keto diet is compared to a typical low carb diet (which is higher in protein than keto)? In this case, the differences on blood sugar disappear.

            One very thorough meta-analysis did just that comparison, and they found that as far as blood sugar control is concerned, there was no difference between a keto diet and a typical low carb diet. They both worked equally well.

How Does Ketosis Affect Athletic Performance?

            In short: not well. The research is fairly conclusive on this one: the keto diet is not the best diet if your goal is sports performance.

            In one study, participants were divided into 2 groups:

• Group 1: keto diet. They consumed 9% of their calories from carbs
• Group 2: high carb diet. They consumed 63% of their calories from carbs

Both groups ate the same number of calories. They both did a cycling test. Group 1 did not do well at all compared to group 2. They:

• Had 7% less power
• Covered 15% less distance.

And this is not the only study that shows decreases in performance on a keto diet.

But keto proponents will often tell you that “when adapting to a keto diet, sure performance drops initially, but after you’re adapted, performance rises.” What they don’t mention is how high it rises. According to the research, performance rises so high that it comes back to… baseline. At best. In other words, performance after fat adaptation is not any better compared to before a high-fat diet.

In one study, the researchers concluded “training intensity may be compromised in individuals while consuming a fat-rich diet.”

Another study concluded that the “Ketogenic diet benefits body composition and well-being but not performance.”

So the overall picture is clear: if you’re an athlete, and your performance is really important to you, the keto diet is not the way to go. But if you’re just a regular exerciser, and longer distances, and faster times are not a priority for you, it may be just fine.

 Can you Eat More Calories on Keto and Still Lose Weight?

            This is a question often asked, because of the observation that people often don’t feel hungry or count calories, and still end up losing weight. But just because people don’t feel hungry doesn’t mean their calories are the same as before. Calories have to drop in order to lose body fat. I go over this in much greater detail in my article on the (un)surprising truth about why we get fat.

            So no, you can not eat more calories on keto and still lose weight. In fact, if you eat more calories than you expend, you’ll gain weight (surprise! Not!).

 

Adherence to the Keto Diet

            To prove that a diet works is no problem. Any diet that restricts calories in one way or another (whether it’s limiting carbs, limiting fat, limiting protein, the “no white” diet, etc.) will make you lose weight. Nothing really new there.

            The real challenge is long term adherence. All diets work, but very few diets work long term.

            There’s a funny meme going around the web that says “I have a condition that prevents me from going on a diet: I get hungry.” And that’s the problem with most diets. They work only until you get hungry.

            Does the keto diet have some special property that suppresses hunger? The research is fairly mixed on this issue, and seems to be leaning towards “no, nothing special.”

            From a mechanistic perspective, the high fat component of the keto diet seems to suppress the hormone ghrelin, according to this study. Ghrelin is the hunger hormone. When it’s high, you’re hungry. Seems good so far.

            On a practical level, however, one study found that after your first “cheat meal” (whether accidental or planned), hunger and ghrelin go through the roof, and you gorge on all the foods you’ve been restricting: pizza, cookies, cake, ice cream. You know, all the delicious stuff.

            However, it is fairly well established that higher protein diets tend to have better long term adherence than lower protein diets, because protein is more filling than either fat or carbs. So considering that the keto diet is a low protein diet, adherence to it long term would be lower than to a higher protein diet.

 

Why Is the Keto Diet So Popular?

            As you can see, the keto diet can be a good diet for the right person, at the right time. It’s a good diet. It’s not the best diet, because there is no best diet. And just as with any diet, it’s not just about the diet itself, it’s just as much about the person themselves undertaking the diet:

·         What are their goals?

·         What are their pre-existing medical conditions/health status?

·         What is their activity level?

 

All these factors, and others will determine whether the keto diet is healthy or not.

Given the lack of the “wow factor” for the keto diet, why do I think it’s so popular? Two reasons:

1.      Rapid weight loss. But let’s remember – weight loss is not fat loss. Because it is inherently a low carbohydrate diet, you lose a lot of water on the diet. That’s not dehydration, rather, you’re just storing less water, because every gram of glucose comes with approximately 3 grams of water (remember, the word is “carbohydrate”). So if you lose a pound of glucose, along with it, you lose 3 pounds of water. None of that is fat. But it looks good on the scale.

2.      It’s cool to say the word “ketogenic” when others around you don’t know what it is. Makes you look trendy, health-conscious and cutting edge (even though the diet goes back to the 1920s).