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Keto Diet: Everything You Should Know Before You Start

Welcome to our keto diet guide for beginners.

Caroline Igo Editor
Caroline Igo (she/her/hers) is a wellness editor and holds Sleep Science Coach and Stress Management certificates from the Spencer Institute. She received her bachelor's degree in creative writing from Miami University and continues to further her craft in her free time. Before joining CNET, Caroline wrote for past CNN anchor, Daryn Kagan.
Expertise Vitamins and supplements, nutrition, sleep & personal care Credentials
  • Carl R. Greer/Andrew D. Hepburn Award for Best Nonfiction Essay (Miami University, 2021)
Caroline Igo
Medically Reviewed
Reviewed by: Amelia Ti Medical Reviewer
Amelia Ti is a Registered Dietitian (RD) and Certified Diabetes Care and Education Specialist (CDCES) based in NYC. She completed her Bachelor's in Nutrition & Dietetics at NYU and Master's in Applied Nutrition at Russell Sage College. Amelia's evidence-based knowledge and passion for the field allow her to translate nutrition research and innovation to the public.
Expertise Nutrition, dietetics, diabetes care, nutrition innovation. Credentials
  • Registered Dietitian
  • Certified Diabetes Care and Education Specialist
  • New York University, BS in Nutrition & Dietetics
  • Russell Sage College, MS in Applied Nutrition
6 min read
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The ketogenic diet is an eating plan that's been used to battle weight issues as well as general health issues. For example, many epileptic patients have seen a reduction in symptoms when following a ketogenic -- or close to ketogenic -- diet. Others have given the diet credit for helping them drop a significant amount of weight in a short time.

Even though there are many potential health benefits associated with a ketogenic diet, it isn't for everyone. In the early stages of low-carb dieting, some people may experience nausea, dizziness, brain fog and overall lack of focus.

For those considering jumping into keto, the diet requires some preparation and forethought before going full speed ahead. If you decide that keto is right for you, preparation will put you at an advantage and allow you to see safer results. 

Here is everything you need to know about going keto. 

Read more: Best Keto Snacks to Buy Online

What is the keto diet?

Whether you're trying it out for weight loss or health benefits, a keto lifestyle is not something that should be taken lightly. Keto requires the elimination of complex carbohydrates, grains, sugar, fruit and tubers, like yams and sweet potatoes. It relies on the heavy presence of meat, leafy greens, above-ground vegetables, nuts, fats, oils and alternative sweeteners. On average, macros on a keto diet should be about 55 to 60% fat, 30 to 35% protein and 5 to 10% carbohydrates. If you were eating 2,000 calories per day, for example, that'd include just 25 to 50 grams of carbs a day.  

While a keto diet may seem very restrictive, it is fairly easy to get creative with meal planning. Some examples of keto-friendly meals include:

  • Chicken lettuce wraps
  • Broiled salmon
  • Stuffed peppers
  • Chicken soup
  • Cobb egg salad
  • Grilled shrimp with zoodles
  • Beef tenderloin
  • Garlic and parmesan zucchini
  • Fried eggs
  • Pulled pork
  • Crustless ham & cheese quiche 

Steak and butter are on the menu on keto.

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How does keto work for weight loss?

By eliminating carbohydrates from your diet, your body is deprived of the ability to burn sugar for energy. Instead, the body breaks down fats in the liver. This metabolic process that the body goes through due to the starvation of carbohydrates is called ketosis

"When you see the body switch from burning glucose to burning ketones … a number of interesting things happen," explains Dr. Mark Hyman, MD, medical director at Cleveland Clinic's Center for Functional Medicine. "One, your metabolism speeds up. Two, your hunger goes away. Three, you turn on the ability of a fat cell to release fat, and burn fats, which increases fat burning, whereas carbohydrates actually shut off fat burning. It literally locks the fat in your fat cells," Hyman said. 

It is through this process that those on a keto diet often see such fast weight loss results and body fat reduction. It's important to note that many other factors go into weight and weight loss, aside from diet -- like stress, hormones and genetics.


The keto diet involves a lot of planning what you're going to eat and prepping your own meals.

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Where to begin your keto journey

There is simply no way around it -- keto requires a lot of planning and prep. Not only will you eliminate foods from your diet, but you will also learn to cook using keto-compliant foods and how to order when dining out. Before you make any drastic changes to your diet (which keto definitely is), it's important to consult with a healthcare professional. 

Here are a few steps to take to begin your journey with keto.

Talk to your healthcare provider

Before jumping on the keto bandwagon, health experts urge you to talk to a doctor or other health professional to avoid any health risks or side effects. This is especially important if you have preexisting health conditions, or if you have a history of disordered eating.

"The diet may be harmful if you have existing kidney, liver or heart disease. If you have diabetes or high blood pressure and are on medications, you should be in close contact with your physician to monitor changes and adjust medications as needed," says Diane Vizthum, a dietitian at the Adult Epilepsy Diet Center at Johns Hopkins.

Find a food tracker

"It can be harder to manage your diet because you might have to spend more time calculating your carbohydrate intake and spend a lot of time planning meals and considering the foods you are eating," says Mascha Davis, a national media spokesperson for the Academy of Nutrition and Dietetics. 

When preparing to start a keto diet, the first step is to find a way to track your carbohydrates. Many turn to iPhone and Android apps to help. Some of the more well-known keto apps include Total Keto Diet, Senza, Carb Manager and Cronometer.    

Stock your cabinets

Stocking your cabinets with keto cookbooks and keto staples can help to eliminate some of the stress of planning and preparing your meals. Researching keto-compliant recipes and learning how to read labels for pitfalls such as hidden sugar will also ensure you will see success on your keto plan. 

Prioritize whole, minimally processed foods

Vizthum adds that when you're on the keto diet you should make an honest attempt to eat whole foods and avoid relying on heavily processed foods that may be keto-compliant, but are otherwise not doing much for your nutrition. Eating whole foods will help you with weight loss and overall health-based results.

Get familiar with macros

On the keto diet, counting macros is really nonnegotiable, especially if your aim is to lose weight. One of the best ways to do this is to use the keto formula, experts say. The formula is your basal metabolic rate (using the Harris-Benedict equation) times your activity level. This will give you the number of calories you should be taking in if you are looking to maintain your current weight. Adjustments may be necessary based on how much weight you are looking to lose and how quickly.

Learn the keto-based substitutions 

Especially for baked goods, snacks and other indulgences, it is helpful to know keto-friendly substitutions. These include stevia, yacon syrup and monk fruit. Unfortunately, honey, agave, coconut and maple syrup are not keto.  


On keto, you'll eat plenty of fat and protein and almost no carbs.

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How do you know you're in ketosis?

There are several ways to figure out if you're in ketosis. The easiest way is to pay attention to symptoms, which tend to include:

  • bad breath 
  • increased urination 
  • dry mouth 
  • increased focus
  • fast weight loss
  • decreased appetite
  • insomnia

If you want to get even more accurate, there are blood and urine tests for those doing keto. Just grab a box of urine strips designed for diabetics, which are widely available at drug stores. Or use a glucose or ketone meter for more accurate results. 

Beware of keto side effects

Side effects may vary from dehydration, acidosis (an influx of acid in the body), constipation, pancreatitis and low blood sugar. However, there is one you should really watch out for: keto flu. This condition stems from the elimination of carbohydrates and sugar, which causes withdrawal symptoms. These can include headache, fogginess, dizziness, lack of energy and nausea. Fortunately, keto flu is a temporary condition that can last anywhere from a couple of days to a couple of weeks

Should you try a keto diet?

If you're trying to lose weight, the keto diet may help you achieve results. For many, this is true, and they even find that keto gives them more energy during the day. But, a ketogenic diet is not for everyone. Here are a few points to determine if a keto diet is right for you.  

A few reasons to try a keto diet include:

Keto diet drawbacks to keep in mind:

  • The long-term effects are still not known due to lack of studies
  • Side effects include keto flu
  • National Lipid Association concluded in 2019 that low carbohydrate diets are not superior to other weight-loss diets
  • As with any strict diet, it can be hard to follow consistently and its rigid rules may trigger disordered eating 

This story was originally written for CNET's former sister site Chowhound by Emily Cappiello in 2019 and has been extensively updated by Caroline Igo. 

The information contained in this article is for educational and informational purposes only and is not intended as health or medical advice. Always consult a physician or other qualified health provider regarding any questions you may have about a medical condition or health objectives.