The Beginner’s Guide to the Ketogenic Diet

Photo: Stocksy/Darren Muir
Chances are, there's a 98 percent chance* that you know someone—your best friend, mother, former high school classmate who is involved in a pyramid scheme—who has embraced the low-carb/high-fat diet known as the ketogenic diet. (*Based on my very unscientific, but probably accurate, real-life observations.)

Only unlike that MLM company Becky from freshman year bio keeps spamming you about on Facebook, the keto diet could actually be a positive thing for you. A growing body of research has shown that our bodies need fat to thrive, which explains why the ketogenic diet—which emphasizes fats and strictly reduces carb intake—is having a serious moment. (And nearly every celeb, from Halle Berry to Vinny from Jersey Shore, is on board.)

While a diet filled with avocados, EVOO, and butter may sound like a true gift, there are a few super-important rules—and icky side-effects—that you need to know about. Keep reading for the ultimate guide to the keto diet for beginners.

What is the keto diet, exactly—and does it have any benefits?

The ketogenic diet is essentially a very low-carb, moderate protein, high-fat diet, said Tracy Lockwood Beckerman, RD, on a recent episode of Well+Good's You Versus Food. It's designed to force your body from burning carbs from fuel into burning fats. The eating plan was invented in the 1920s as a way to help treat children who had severe forms of epilepsy, but was adapted by the mainstream more recently as a potential way to manage weight, improve hormone and energy levels, and more.

How does it work, exactly? “The most important thing to know before embarking on the ketogenic diet is that you need to keep your carb intake under 30 grams total per day,” says Keto Comfort Foods author Maria Emmerich. That's because the absence of carbohydrates forces the body into—and keeps it in—ketosis, the metabolic state key to the ketogenic diet. When your body is in ketosis, it switches from using carbs as its primary source of energy and instead uses ketones (fats) as its energy source. “This enables you to tap into greater energy reserves, improves your moods, and allows you to burn excess body fat,” Emmerich says.

Achieving ketosis requires very strict management of the various macronutrients—carbs, fats, and protein. Again, carb intake generally is not supposed to exceed 30 grams per day. Then, Emmerich says people should eat about 0.8 times their lean mass in protein every day. “A woman who weighs 150 pounds and has 30 percent body fat has about 105 pounds of lean mass, so she would shoot for 84 grams of protein each day,” says Emmerich. Fat should clock in somewhere around 90 to 100 grams per day.

The alleged benefits of keto include weight management, increased mental clarity and energy, and balanced hormone and blood sugar levels. However, the tricky part is that a lot of these benefits are anecdotal—most of the research done on keto has either been specifically performed on children with epilepsy (making it not applicable to the general population), or aren't long-term studies (so we only know the short-term potential benefits and downsides of the eating plan).

Some potential benefits, per Beckerman, include:

  1. Increased satiety. Eating lots of fats can help you stay full for longer, Beckerman said in the episode, which can help prevent overeating. They also decrease appetite-stimulating hormones.
  2. Improved insulin sensitivity. Eating fewer carbs in general, Beckerman said, can help stabilize blood sugar levels and may help reduce a person's risk of diabetes.
  3. Better mental performance. This isn't necessarily due to the nature of ketosis, but rather the fact that by consuming healthy fats high in omega-3s (as is encouraged on this eating plan), you're supporting brain and cognitive health. It can also improve mood and keep it stabilized.

Wondering what an RD thinks of the ketogenic diet? Look no further...

What you do and don't eat on the keto diet

The short version: expect to eat way less pasta, bread, and other carbs, and a lot more fat. “Your pantry won’t look a whole lot different—just remove all the carb filled junk,” Emmerich says. Here are some low-carb basics she says your new-and-improved keto kitchen will need:

  • Coconut oil and/or MCT oil
  • Ghee
  • Grass-fed butter
  • Olive oil
  • Grass-fed beef
  • Line-caught fish
  • Organic chicken
  • Eggs
  • Non-starchy vegetables like spinach and Brussels sprouts
  • Almond flour (Emmerich says this is a great tool for putting a keto-friendly spin on your favorite desserts

Meanwhile, these are examples of the carby foods you should not eat on the keto diet:

  • Bread, pasta, rice, and other grains
  • Starchy vegetables like sweet potatoes and corn
  • High sugar fruits like mangoes
  • Lentils, peas, and other legumes
  • Juice, soda, and other sugary drinks
  • Added sugars of practically any kind

While a few natural sweeteners are fair game on the diet, including stevia, xylitol, and monk fruit, Emmerich recommends avoiding them, too, while you adjust to this new way of eating. “Abstain from all sweet flavors for a month; this will shift the palate away from sweet tastes,” suggest Emmerich. “At the end of the month, you’ll find that sweet flavors won’t cause so many cravings, even when using healthy natural sweeteners in moderation.”

Are there any side effects to keto?

The main side effect of keto is that you're required to post on Instagram stories about how delicious your cauliflower pizza crust is, and how you totally don't miss carbs because it's just as good as real pizza crust (even though everyone knows that's false). I know because it happened to me.

But real talk, there's also this thing called the "keto flu" which is pretty much exactly what it sounds like. "During the first one to two weeks of the keto diet, it's common to experience a number of symptoms as the body adjusts to using fat for energy instead of glucose," says Josh Axe, DC, author of the book Keto Diet. The main side effects, Dr. Axe says, are fatigue, brain fog, headaches, trouble sleeping, constipation and indigestion, trouble sleeping, less motivation to exercise, irritability, and increased urination and moodiness. Cool. (Again, you will probably feel inclined to post about all of this dramatically on Instagram stories. This is all very normal.)

While you're at it, maybe stay off your dating apps for a while—or, at least, don't schedule any dates during this two week period. There's this fun thing called "keto breath," where your breath stinks worse than old garlic during the transition into ketosis. This admittedly does not lend itself well to romance (not that I'm speaking from personal experience or anything).

Some people's digestive systems are also sensitive to eating lots of fats, which might result in another phenomenon called keto diarrhea. Again, this should be temporary and should only last for a few days—but if it persists, talk to your doctor ASAP.

Headaches are also really common, but can be prevented by upping your water intake and adding electrolytes into your diet. “[The headaches] are primarily due to dehydration, because your body retains water when you’re on a high-carbohydrate diet,” explains Emmerich. “Going into ketosis will release much of this water along with electrolytes.” Make sure to sip on tons of H20 along with coconut water (which naturally has electrolytes), and you should be able to manage the first few weeks without relying on a steady dose of aspirin.

Common keto mistakes to avoid

Dr. Axe says that there are three major mistakes people make when they embark on a keto diet that could be affecting their experience on the eating plan (and their results). First up: not eating enough non-starchy veggies. "We need vegetables in our diet to obtain fiber, vitamins, and electrolytes that help prevent side effects," he explains. "Non-starchy veggies like leafy greens and cruciferous vegetables should be eaten throughout the day."

Dehydration is another thing to watch out for. "Urination is increased on the keto diet, and electrolytes are lost at an increased rate," Dr. Axe says. He says it’s important to drink lots of water, and consuming salt (an electrolyte!) by adding sea salt to your food and drinking bone broth.

Last, he says people often make the mistake of using a high-fat diet as an excuse to eat tons of processed food (there's a reason why keto is known as the butter-and-bacon diet.) "A clean approach means focusing on whole, unprocessed foods (like olive oil, grass-fed butter, avocado, cage-free eggs, fish etc.), limiting processed meats and refined vegetable oils, and incorporating vegetables into the diet too," Dr. Axe says. That way you’ll enjoy the results of ketosis without missing out on major nutritional components that your body needs.

Prepare to make long-term changes

Think the keto diet is a “one-and-done” kind of deal? Not necessarily! You may just be testing the waters or taking on a 30-day challenge, but know that many people wind up making the keto diet a permanent lifestyle change.

“Most of my clients are amazed at how good they feel after starting this diet,” says Emmerich, adding that many experience healthy weight loss. “Once people realize how great they feel on a keto diet, they’ll likely try to stay keto for life.”

However, a lifetime of keto eating is not recommended for everyone, so it’s best to listen to your body and talk to your doc. "Typically it's recommended that a traditional keto diet be followed for about two to six months, or perhaps for about a year if someone has a lot of weight to lose and is responding well," Dr. Axe says. "In some cases, if a patient with a health condition (such as diabetes or epilepsy for example) is working with a doctor, they might follow the diet for longer, such as one to two years.” He adds that most people will see results like weight loss, improved mood, and better mental clarity in six months or less. After that, people may choose to carb-cycle moving forward—"meaning they increase carb intake about 1-2 days per week to restore their glycogen stores," he explains.

Ready to try it? Check out one of Emmerich's go-to keto recipes, below.

Beginner's guide to the ketogenic diet
Photo: Maria Emmerich

Basil deviled egg recipe

Serves 6

12 large eggs
1/2 cup basil mayonnaise (see below)
1 tsp coconut vinegar or apple cider vinegar
1/2 tsp fine sea salt
6 cups mixed greens, for serving
12 cherry tomatoes, halved, for garnish
Fresh basil leaves, for garnish
3/4 cup easy basil hollandaise (see below)

Basil mayonnaise
1 cup coarsely chopped fresh basil leaves
3/4 cup mayonnaise
1 clove garlic, crushed to a paste
1/4 tsp fine sea salt

Easy basil hollandaise
1 cup loosely packed fresh basil leaves
1 cup bacon fat, beef tallow, or leaf lard
4 large egg yolks
1/2 cup lemon juice
1/2 tsp fine sea salt
1/4 tsp fresh ground black pepper

1. Make the basil mayonnaise: Place the basil in a food processor or blender and puree until smooth. Add the mayo, garlic, and salt and pulse until well combined. Place in a jar, cover, and store in the fridge for up to one week.

2. Hard-boil the eggs: Place the eggs in a large saucepan and cover with cold water. Bring the water to a boil, then immediately cover the pan and remove it from the heat. Allow the eggs to cook in the hot water for 11 minutes.

3. After 11 minutes, drain the hot water and rinse the eggs with very cold water for a minute or two to stop the cooking process. Peel the boiled eggs and cut them in half lengthwise. Remove the yolks and place them in a bowl (or a food processor). Mash or blend the egg yolks with a fork (or a food processor) until they are the texture of very fine crumbles.

4. Add the basil mayonnaise, vinegar, and salt to the egg yolks and stir to evenly combine. Fill the egg white halves with the yolk mixture.

5. Divide the mixed greens among 12 plates and place 2 deviled eggs on each plate. Garnish with cherry tomato halves and basil leaves and drizzle each deviled egg with 1½ teaspoons of basil hollandaise, if desired.

6. Keep leftover deviled eggs in an airtight container in the fridge for up to 3 days.

Basil hollandaise

1. heat the fat in a small saucepan over high heat (or in the microwave) until very hot and melted. Set aside.

2. Combine the basil, egg yolks, and lemon juice in a blender and puree until very smooth. With the blender running on low speed, drizzle in the hot melted fat until a thick, creamy mixture forms. Add the salt and pepper and pulse to combine; adjust the seasoning to taste.

3. Use immediately or keep warm for up to 1 hour in a heat-safe bowl set over warm water. Store in a covered jar in the fridge for up to 5 days. Reheat the sauce in a double boiler or a heat-safe bowl set over a pot of simmering water, whisking often, until the sauce is warm and thick.

Recipe excerpted with permission from The 30-Day Ketogenic Cleanse by Maria Emmerich. For more support and keto information go to

This piece was originally published on January 22, 2018. It was updated on March 19, 2020.

You may also want to shift your workout routine while eating keto—here's why. (Throw one of these grain-free bars in your gym bag to fuel up before you sweat.) 

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