(Diet Review) Is The Ketogenic (Low Carb High Fat) Diet Safe and Sustainable?

I was trained in nutrition school to vehemently oppose ketogenic (otherwise known as low carb, high fat or #LCHF) diets. The very mention of a zero carb diet makes most dietitians recoil, and I was no exception. Ketogenic diets have generally been recognized among nutrition professionals as being unsafe, unsustainable, and inadequate in nutrients.

But are they?

A lot of people have asked me this question, so I’m going to review the ketogenic diet for use in weight management and overall wellness. There are other uses for this diet (ie epilepsy and brain injury) which I won’t be talking about here.
Ready? Here we go!

What is ketosis?

The quick and dirty answer is: ketosis is when your liver turns fat and certain amino acids into ketones to fuel your body, because no carbohydrate (or, under 50 grams a day for most people) is available. One thing must be said: dietary ketosis is NOT diabetic ketoacidosis, so let’s not make that mistake. Without going into detail, people who produce insulin don’t go into ketoacidosis, which can be fatal.

Moving on. When you eat adequate carbohydrates, your body and especially your brain, will use them as glycogen as its first source of energy. Carbohydrates are easy for your body to convert to energy, and generally anything alive will always choose the easiest path it needs for anything.

Your brain in particular loves glucose. The brain is equipped to use only two fuels to function: glucose or ketones. When glucose is unavailable, ketones are its next best option. So, your body starts producing them, because without your brain, you’re dead.

Magically, without any carbohydrates consumed, your body can derive some glucose from fatty acids and amino acids. Isn’t nature wonderful?

So how do you send yourself into ketosis? You don’t eat anything at all, which is unacceptable. Or, you eat a diet that’s ketogenic – essentially lower than 30-50 grams of carbohydrate per day and going as low as possible, actually – to maintain yourself in a state of ketosis. What does 50 grams of carbohydrate look like? In whole food terms, that’s (one of the following):

1½ apples

4 slices of bread

Just over a cup of quinoa

Around 1 cup of rice

But before you start thinking that 4 slices of bread a day doesn’t sound too bad, don’t forget that you get carbs not only from the obvious ‘carb foods’, but also from some other foods as well. A ketogenic diet means watching *all* foods carefully for carbs, even in things like nuts and seeds and non-starchy vegetables. As in, green beans have 2.6 grams of carbs per cup and almonds have 2.5 grams of net carbs (the carbs minus the indigestible fiber) in an ounce. Fact like this seldom matter to people, but people on a ketogenic diet become intimately acquainted with the net carb value of many, many foods.

When you’re counting every single carb that’s passing your lips, you end up choosing bok choy over broccoli because broccoli is higher in carbs. Sounds exhausting…almost as exhausting as resisting cake on my birthday. No cake of the ketogenic diet, obvs.

It’s all about the macros, and it’s not high in protein

One huge misconception that many people have about the ketogenic diet is that it’s a high protein diet. It’s actually not. Low carb high fat diets are around 70-80% FAT (lots of it saturated, from cheese and meat), along with around 20% protein and around 5% carbohydrate. The ‘macros’ – meaning carb, protein, and fat – or macronutrients, differ slightly between different sorts of these particular diets, but in general the ones above are typical.

One of the benefits of a ketogenic diet is that ketosis causes a reduction in appetite, so you may not be very hungry while you’re eating this way. This could be considered a plus when you’ve sworn off 90% of the food that other people are eating.

What does a typical day in the life of a low carb high fat diet look like?

Something like this:

Breakfast: tomatoes with cottage cheese, bacon and eggs, or some concoction involving all of the above

Lunch: a sandwich made with cloud bread (learn more here, yum yum) with meat and low-carb vegetables, or a pizza made with cheddar cheese crust and meat and more cheese and some low carb vegetables.

Dinner: cauliflower whipped ‘potatoes’ with chicken or another meat/fish and a salad.

Snacks: ‘fat bombs’ – which basically exist to ensure that you reach your 80% fat level. I’m not going to lie, some of these look amazing, despite the fact that they use stevia or xylitol, which I find have an aftertaste. Essentially these bombs are made up of any combination of coconut oil, coconut, peanut butter, unsweetened cocoa, sweeteners, and spices like cinnamon or lime or whatever taste the maker is attempting to achieve. If you search the term ‘fat bomb’ on Google you’ll see what I’m talking about.

People on a ketogenic diet also snack on plenty of nuts, coconut, low-carb vegetables, eggs, avocado, and pan-fried cheese. It’s not as though there isn’t choice…you just might not be eating the sorts of foods that you’d enjoy as part of a normal diet (aka sushi and after work drinks with your friends), and that’s something that you’ll need to get over pretty quickly.

Is the ketogenic diet inadequate in nutrients? It does tend to be low in fiber for some people, and because people tend to lose water on this diet, at least initially, you really need to watch your electrolytes (I’m talking about you, sodium and potassium). Overall though, the diet contains dairy, meat, some fruits, vegetables, fish, and healthy (and maybe not so healthy too) fats. There are nuts and nut butters and eggs. Ketogenic diets don’t include legumes and grains, alcohols, and sugars.

There’s not a lot of evidence to show that this particular diet is lacking in major nutrients. Even so, that doesn’t make me want to promote this diet over other ways of eating, because this fact is only one piece of the puzzle. Which leads me to….

The health effects of a ketogenic diet

I think the first thing in any non-ketogenic dieter’s mind is the question, “isn’t this diet like a heart attack waiting to happen?!”

I hear you. So let’s see.

Now, I know this is where you expect me to put my dietitian hat on and wag my finger, saying that this diet is sooooo unhealthy and that you need to eat 60% of your diet in carbs. I’m actually not going to do that though! Aren’t you surprised?

It just so happens that for the average healthy person, a ketogenic diet shouldn’t really cause much harm. Not that I’m promoting yo-yo dieting or dieting at all, but if you’re curious and wedded to the idea of trying this diet, then there’s no reason why you shouldn’t try it if you’re healthy. Healthy being the operative word here, as I do recommend that you consult your doctor first.

I also recommend that you temper your expectations right off the bat. There are all sorts of miracle claims out there that ketogenic diets can cure everything from cancer to acne, but the research isn’t there.

Ketogenic diets will likely affect your workouts. Now, I’m 100% sure I’m going to get a ton of hate mail from all the #LCHF people out there, but yes. The research still confirms that for most people, a diet that contains carbohydrates is best for athletic performance for the majority of people. I stand firmly on the side of carbs for energy and sports. Nanci Guest, a Sport Dietitian and PhD candidate at the University of Toronto, has this to say on carbohydrate and performance:

Nutrition advice for athletes needs to be personalized, and specific to what they are doing in training. Certainly lower carbohydrate days are warranted on rest or light days, but on most training days or during competition “Carbs are King”. Although 99% of sport nutrition researchers around the world agree on this point, it seems the 1% often get a louder voice usually through social media (which is not science by the way)

Over the past 2 decades numerous studies have been done in athletes and exercising individuals to better understand the potential of ketogenic diets – providing around 80% energy from fat, moderate protein intake, and less than 50g per day of carbohydrate – because it sounds logical that you have an endless amount of fat calories to burn so why not take advantage of that. But it’s not that simple: following a high fat diet changes your metabolism where the body becomes incapable of breaking down carbohydrates properly. If you are going for a power walk, easy jog or bike ride sure you can rely on mostly fat, but if you want to run, climb hills, play tennis or hockey or soccer, do interval training, lift weights or anything else moderate to high intensity your “power” muscle fibers need carbs, period. A high-fat diet impairs your ability to work-out or play sports at a higher intensity. In essence you take away your body’s top gears because they require carbs. If you’re sedentary perhaps this approach might work for you but don’t forget MOST of us are not meeting our physical activity requirements.

Let’s talk about weight loss and low carb, high fat diets

When a person goes on a ketogenic diet, they typically dump a bunch of water first, which accounts for the initial rapid weight loss. After that, weight loss may occur because this diet cuts out a heck of a lot of foods out there, and the diet may end up being fairly low in calories. Low carb high fat people are not going around eating chips, crackers, Starbucks croissants, Coke, your favorite thin-crust pizza, bottles of wine, and plates of pasta. They’re not popping frozen chicken nuggets into the toaster oven or ordering Thai noodles.

Nope nope nope.

Instead, they’re eating a shit-ton of vegetables and fat. And they’re getting full, because the consumption of fat and protein spurs the release of CCK, which is a satiety hormone. As I said earlier, ketogenic diets also use fat for fuel, so you’re essentially getting rid of the fat you’re packing.

Some research (and here and here and here and here) shows that a ketogenic diet can help with weight loss. Some research shows that it sort of doesn’t, but yes – the research for weight loss on a ketogenic diet is promising. I say that with a grain of salt, though, because keep reading.

The general feeling among many people is that fat makes you fat and sick. Leave that thinking in the 90s, because that ship has sailed.

In fact, cardiovascular risk factors like elevated cholesterol (and here) don’t appear to be an issue for people who maintain a low carb high fat diet. That being said, there’s not many studies on specifically low carbohydrate (as in, 5% or less of total calories) high fat diets, so we need to be mindful of this. I spent a crapload of time searching for literature about ketogenic diets, and came up empty. Lots of studies look at low carb diets, but not low carb with 80% of calories from fat. So there’s that to consider when interpreting the research. And remember – saturated fats are still suspect. They’ve never been vindicated completely, even though they may not be as harmful as we once thought. Mostly, studies about fats show the irritating ‘more research needed’ result that leads me to recommend a wide variety of fats to my clients. We’re just not 100% sure.

The downside of low carb, high fat diets

So why am I not running out and recommending this diet to everyone?

First off, I’m not big on diets in general because in general, they don’t work. So, there’s that. Also, I did not see a research study on low carb high fat diets that went over 24 months, so we aren’t sure about the long-term effects of this beyond two years. That makes me a bit nervous, although it’s pretty rare to see someone on this diet for even that long.

The ketogenic diet is extremely strict. You need to maintain ketosis, which is why the diet works; if you aren’t an organized person who shops and plans your diet out, you may have issues maintaining this diet for the long term.

There will always be people who are outliers aka who don’t need carbs for their workouts, who can maintain a relatively carb-free diet for 100 years, and who don’t care about never eating birthday cake again. Those people are few and far between, and they’ll do great on this diet. I’m sure lots of them are going to flood my social media and inbox with their comments about how great this diet is. For the majority of the population though, a ketogenic diet isn’t sustainable, and will likely result in the weight regained once the diet is abandoned. So consider yourself warned.

In short, the best diet for YOU is the one that won’t harm you, that enriches your life and lets you love food, one that won’t affect the other parts of your life – like your sleep, your social life, and your relationships, and most of all, that you can stick to in the long term.