Fact-checked by Dr. Anthony Gustin, DC, MS.
Written by Emily Ziedman
Within a week or two on a ketogenic diet, you’re going to notice more energy, steady blood sugar, more mental clarity, and likely some weight loss too. Not bad for a simple short-term shift in your diet. But what happens after a few months, years, or decades on a low-carb, high-fat diet? Is this type of diet sustainable long-term?
What Is Ketosis?
Ketosis is a metabolic state in which your body burns fat for energy instead of carbohydrates. While your body typically uses glucose (from carbohydrates) as its main source of fuel, in ketosis your body burns ketones ( from fat) instead.
To achieve this metabolic shift, you need to follow a high-fat, adequate protein, and low-carbohydrate diet known as the ketogenic diet.
Getting into a ketogenic state is not as simple as switching up a meal or two. Unlike some diets where you can dip a toe in to see if it’s for you, ketosis takes a little more time and commitment.
So why are so many people taking the time to switch their metabolism to fat burning mode? Overwhelmingly, the results are worth it.
Everyone’s body is different, but the guidelines below will give you a general idea of what your diet should look like if you want to get into ketosis. Keep in mind that limiting carbohydrates is the key.
If this is your first time reading about the ketogenic diet, check out this complete Ketogenic Diet Guide for more information.
What You Can Eat On Keto
- Protein: When it comes to protein on the keto diet, pastured meat and fatty fish are the default. Say goodbye to high-carb beans and soy. Look for fatty cuts of organic meats like grass-fed beef, chicken, pork, lamb, goat, turkey, veal, wild fish sources like salmon, mackerel, sardines, and tuna, and organic whole eggs.
- Fats: Healthy fats will help you stay fuller longer and won’t kick you out of ketosis. Include plenty of olive oil, avocado oil, coconut oil, ghee, grass-fed butter, avocados, nuts and seeds into your keto diet.
- Dairy: Full-fat cheeses, sour cream, full-fat (unsweetened) yogurt and heavy creams are allowed on a keto diet. Just make sure your sources are high quality and that you get the bulk of your calories from other healthy foods.
- Low-carb vegetables: Get plenty of veggies like spinach, kale, broccoli, cauliflower, asparagus and other leafy greens on your keto diet.
- Low-sugar fruits in moderation: Small quantities of blueberries, strawberries, raspberries are allowed on a keto diet, but watch your carb intake.
What You Don’t Eat On Keto
- Whole grains and processed grains: Whole and processed grains like wheat, rice, millet, corn, barley, rye, oats, and quinoa are too high in carbs for a keto diet. Even a half cup of a lower-carb grain like quinoa contains a whole day’s worth of carbs — about 20g. Probably best to avoid them altogether.
- Beans and legumes: Most beans and legumes are high in carbohydrates with a modest amount of protein and a very small amount of fat.
- High sugar/ lower fiber fruits: Most tropical fruits like pineapples, mangoes, papaya, and tangerines are high in sugar and will kick you out of ketosis. Avoid tropical fruits and limit even low-sugar fruits like berries. One exception — avocado is considered a fruit but works very well on a ketogenic diet due to its high fat and fiber content.
- Starchy vegetables: Potatoes, yams, carrots, parsnips, and peas are all examples of starchy vegetables that can spike your blood sugar and block ketone production. Best to avoid these.
Is Ketosis Bad For You?
You’ve likely heard some controversies about the ketogenic diet. And it makes sense.
The keto diet encourages fat consumption, and all dietary fat has been villainized in the medical community and the press for the past 70 years.
But despite plenty of controversy and a fair amount of misunderstanding, there’s been an outpouring of positive research backing the ketogenic diet.- Read on for some of the biggest concerns about the keto diet and why getting into and staying in ketosis might be the best thing you can do for your body.
Is The Keto Diet Bad For Your Kidneys?
You may have heard that the keto diet can cause kidney disease or kidney stones.
This misunderstanding comes from the idea that high-protein diets are dangerous for kidney health. And it’s true — if you already have kidney disease, you may want to watch your protein intake.
However, high-protein diets do not pose a risk in healthy people[*].
This point is moot, however, because the ketogenic diet is not necessarily a high-protein diet. While you certainly have to keep your carbs below a certain level, your protein intake will vary according to activity levels and health goals.
Check out this handy macronutrient calculator to find out your unique carbohydrate and protein needs.
Protein aside, there’s actually some pretty compelling evidence that a low-carb diet protects your kidneys.
If anything, chronic high blood glucose is a risk factor for kidney disease — not fat or protein. The main cause of diabetic kidney disease is high blood glucose[*].
And there’s some evidence that a ketogenic diet may help reverse diabetic kidney disease[*].
But what if your kidneys are healthy?
Even if you don’t have diabetes, chronic high blood glucose is a risk factor for kidney disease. So, if you want to keep your kidneys healthy, don’t worry as much about eating a grass-fed steak and focus on keeping your blood glucose levels in check, instead[*].
Is Keto Bad For Your Heart?
The controversy is over. High-fat, low-carb diets are not only safe for your heart, but there’s a pretty consistent flow of new research coming out revealing how a ketogenic diet can protect your heart[*,*].
Studies show that eating a ketogenic diet has beneficial effects on several markers for heart disease and can lead to type 2 diabete[*]:
- High blood pressure
- High cholesterol
- High triglycerides
- Higher BMI
- Chronic high blood glucose
But wait — there’s more. When you’re in ketosis, your body is flooded with an anti-inflammatory ketone molecule called B-hydroxybutyrate (BHB)[*].
And calming inflammation is one of the most powerful things you could do to prevent heart disease and other chronic illnesses.
So, if the keto diet is ok for your kidneys, your heart, and your blood sugar, then what’s the catch? And is keto sustainable for the long-haul?
Some nutrition experts worry that a very low-carb, high-fat diet may have negative repercussions months or years down the line.
Is The Keto Diet Sustainable Long-Term?
Low-carb, high-fat diets are far from dangerous in the short-term. What about over years or decades?
To date, there isn’t much research showing the long-term effects of a ketogenic diet over the course of several years.
That’s partly because the diet has only gained mainstream attention over the past couple of years. It’s also because it’s notoriously difficult to perform long-term nutrition research in humans.
There are just too many variables when it comes to tracking what people eat over the span of years.
With that said, there isn’t any evidence that suggests long-term keto is a bad idea. Let’s look into that a little further.
Ways The Keto Diet Is Sustainable Long-Term
The fact that humans developed the ability to use both ketones and glucose is evidence that metabolic flexibility is innate and natural.
Unlike today where food is everywhere, back in hunter-gatherer times there would be long stretches where food was hard to come by.
When food is lacking, glucose is lacking. And when there’s no glucose for quick energy, then your body naturally turns to ketones for fuel.
Here are just a few scientifically-backed reasons keto may be good for the long-term:
#1: The Science Behind Sustainable Keto
- Blood glucose
- Blood pressure
If your body didn’t like ketones, it’s highly unlikely you’d see so many positive side effects.
#2: Ketosis helps control inflammation
The big concerns with long-term keto are that the diet is hard on your kidneys or may cause chronic illness.
But that’s a tough theory to prove considering keto’s role in controlling inflammation. The ketone body BHB has been studied for its ability to block inflammatory receptors.
That means when you’re in ketosis you’ve got a bunch of inflammation-blocking chemicals flowing through your blood[*].
#3: Ketosis is easier to stick to long-term
One potential drawback to the ketogenic diet long-term is the social aspect.
Keto Precautions Long-Term
Even if it’s safe to stick to a keto diet long-term, there are a few precautions to keep in mind.
#1: Micronutrient Deficiencies
A long-term keto diet could possibly lead to micronutrient deficiencies over the years.
It’s possible to pack a keto diet with nutrient-dense vegetables, fats, and proteins.
But it’s still technically a restrictive diet. And on a restrictive diet, it’s possible that you’ll start to eat the same few foods over and over again.
A lack in food diversity can affect your micronutrient intake.
The best way to make sure you’re covering your micronutrient bases is to eat a variety of low-carb veggies, and switch up the types of meat you’re eating.
If you notice symptoms like fatigue, brain fog, digestive upset, dizziness, or any other unexplainable changes, you might want to check with your doctor about your micronutrient levels.
#2: Nourish your microbiome
On a similar note, a lack of food diversity can also lead to a lack of diversity in your gut microbiome.
Your microbiome, or “gut bugs,” are responsible for a strong immune system, blood sugar regulation, energy production, and even your mood.
While research is ongoing, taking care of your gut bugs is essential to long-term health. And your microbes like fiber. Specifically prebiotic fiber from plants, nuts, and seeds.
The keto diet is not what you might call “fiber forward,” so make sure you’re getting plenty of low-carb veggies, nuts, and seeds.
#3: Make Sure You’re Getting Enough Calories
This is great for short periods of time, but long-term, chronic caloric restriction can do a number on your energy levels and hormone production.
Every few months, you might want to track your caloric intake to make sure you’re getting enough food to sustain your body, your brain, and your workouts.
#4: Supplement When Necessary
- Electrolytes. It’s not uncommon to excrete more electrolytes than normal when you’re getting into ketosis. Electrolytes are minerals that help regulate nerve and muscle function, among other things.
Stay on top of your electrolyte balance — even if you’ve been in ketosis for a while — with a high-quality electrolyte supplement.
- Micronutrients. Even the most diligent person misses out on a serving or three of vegetables in a day. Make sure you’re getting all the micronutrients your body craves with a keto-friendly micronutrient supplement.
- Whey Protein. Keto increases satiety[*], which means your usual drive for food may hit a wall when doing keto long-term.
You may forget to eat or even be turned off by a lot of foods. Whey is a highly bioavailable source of protein that’s easy to drink on the go. Mix up a delicious chocolate whey shake to keep your calories and protein intake in a healthy range.
#5: Avoid a Food Rut
A keto diet is healthy long-term, but is it sustainable from a lifestyle perspective?
You may get sick of always thinking of what you “can” and “cannot” eat. Keto also curbs your hunger, which is great for rapid weight loss, but bad for food motivation.
To keep keto sustainable make sure that you’re eating an array of foods, just like you would on any other diet.
Switch things up, try new low-carb veggies, sauces, and spices. Try new protein sources and challenge yourself to experiment with new recipes.
Pros and Cons Of a Long-Term Keto Diet
The health benefits of a keto diet are hard to argue with.
Keto can control blood sugar, inflammation, cholesterol, and help protect against neurological disorders and heart disease. If you could create a drug that did all that, it would turn the pharmaceutical industry on its head, and you would be a billionaire.
However, if you’re looking for research on the long-term effects of a keto diet, you may have to wait another 10 years.
The bottom line? There is enough research to suggest that nutritional ketosis is healthy long-term. Not just that, but that it may help prevent some pretty horrific chronic diseases.