What is the ketogenic diet?

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If you’re reading this article, chances are you’ve heard of keto. You might even know that “keto” is short for “ketogenic,” as in a ketogenic diet.

And maybe you’ve seen some people passing on the bread basket at dinner, or asking to substitute a salad in place of a potato. Maybe you’ve even had some friends and family that have shed a few pounds and have more pep in their step thanks to “going keto.”

It’s no secret that interest in keto has skyrocketed during the last few years. Keto cookbooks take up more bookstore shelves than ever before and packaged foods that make keto more convenient—like spiralized zucchini noodles and riced cauliflower—occupy an ever-growing amount of supermarket real estate.

So what exactly is the ketogenic diet, anyway? And why is it so popular?

How the ketogenic diet works

cooked fish

Keto is a very low-carb diet. Millions of words have been written going into microscopic detail about this way of eating, but ultimately, that’s the most important and most fundamental thing to know about keto.

Different amounts of protein and fat can be tailored to someone’s individual goals, but what makes a diet ketogenic is a very low amount of carbohydrates—not any particular percentages, ratios, or macros of protein and fat.

Here’s how it works: the names keto or ketogenic are used because when you eat this way, your body generates ketones. While your body uses a few different fuels, depending on the cell or tissue type and whether you’re exercising or relaxing on the couch, typically one fuel will predominate, meaning that you use more of it than the others.

If you put a bunch of carbohydrates in your tank every time you sit down to a meal or snack, your body will primarily burn those carbs. Contrast this with a keto diet: when there’s very little carbohydrate coming in, your body shifts to burning mostly fat. (After all, if there isn’t a whole lot of carbohydrate around, your body better find something else to fuel itself with, right?)

Ketones are molecules that are made as a byproduct of burning fat, so keto diets are like a two-for-one: when you switch from burning mostly carbs to burning mostly fat, your body gets energy from the fat and from the ketones. Nice!        

What is keto good for?

bacon and eggs

The metabolic shift from burning primarily carbs to primarily fat happens mainly due to lower blood glucose levels and even more so the lower insulin levels that result from the lower glucose.

You might be used to thinking of insulin as a “blood sugar hormone,” but lowering blood sugar after a high-carb meal is only one of many jobs insulin performs. It also tells your body whether it’s in a fed or fasted state: that is, whether it has plenty of incoming food to use for energy, or whether it doesn’t have much coming in and should tap into stored body fat to use for fuel instead.

This is why keto is sometimes called a “fasting-mimicking diet.” When your carbohydrate intake is very low, your insulin level will be low-normal most of the time, so you can reap some of the benefits of fasting without actually needing to fast.

That’s right: you can induce some of the metabolic effects of fasting while still eating food—provided your food is very low in carbs.

And if your body—your cells, really—have plenty of fuel available to them from the inside (from your body fat), it would make sense that you might feel less hungry for food from the outside, right? This is why so many people tend to eat just one or two meals a day on keto, sometimes without even having any snacks.

Most people who follow a keto diet report being hungry less frequently than they were on a high-carb diet. Because they’re no longer riding up and down the blood sugar roller coaster all day, they’re able to go longer between meals without feeling shaky or irritable. (To be clear, it’s okay if you do eat three meals a day and/or have snacks, but this explains why so many people on keto don’t need to.)

It’s precisely because keto helps keep blood sugar and insulin levels within a low-normal range that it is so effective for greatly improving or even completely reversing conditions like type 2 diabetes, high blood pressure, metabolic syndrome, polycystic ovarian syndrome (PCOS), non-alcoholic fatty liver disease (NAFLD), migraines, gout, and more.

And of course, keto is well-known to be helpful for weight loss, and it’s still used for one of its original intended purposes: reducing or eliminating seizures in epilepsy. (Ongoing research is looking into whether keto might also be beneficial for other neurological or neurodegenerative disorders.)  

The diet is NOT a fad

cut steak

Naysayers about keto and those who want to talk people out of trying this potentially life-changing way of eating will claim that it’s a fad or that it’s unsustainable. Considering that people have been using low-carb diets for weight loss for over 200 years, it’s hardly a fad. (Take that, bell bottoms and mood rings!)

The first commercially successful low-carb diet guide was published in the 1860s, and the therapeutic power of carbohydrate restriction was discussed in a 1957 paper published in no less than the Journal of the American Medical Association.

As for keto being “unsustainable,” that’s entirely in the eye of the beholder. What feels unsustainable to one person might be an absolute pleasure for someone else—especially if it means potentially improving symptoms from a host of medical issues. 

And in case you’re confused about the safe, therapeutic ketosis induced by a keto diet versus the dangerous ketoacidosis that can happen in uncontrolled diabetes, we cleared this up in a past article. Don’t let a misunderstanding of these very different metabolic states prevent you from trying a keto diet. 

What are you waiting for?

couple smiling

If you’re ready to get off the sidelines and dive in to start reaping the benefits of a keto diet, it’s pretty easy to get started. Check out our guides for 5 practical steps for starting keto and 8 things to know before starting.

Here’s the nutshell version, though: keep it simple! Remember, what makes this way of eating effective for most people is simply keeping your carbohydrate intake very low. That’s it!

You don’t need to weigh and measure your food, track it in an app, use special gadgets and meters to measure your ketones, and you don’t need special keto products or newfangled foods, like MCT oil. You can use all of those if you want to, but it’s perfectly fine to keep things plain and simple.

People have been successful on keto for hundreds of years, long before any of those specialized tools or foods existed.

One word of caution: if you’re interested in keto for more than just weight loss, be sure to get medical supervision before changing your diet if you have medical conditions—especially if you take any medication for diabetes or high blood pressure.

Keto is so powerful and your body may start responding so quickly that doses of your medicines may need to be changed within days of starting. Don’t guess about this and don’t try to manage things on your own. Work with your doctor to adjust your medications safely. (You can search here and here to find a keto-friendly medical professional in your area or one you may be able to work with remotely.)

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