What actually makes a diet 'keto'?

A diet is ketogenic only if it restricts carbohydrates enough to lower insulin and allow the liver to produce ketones. For most people, this means consuming fewer than 50 grams of total carbohydrates per day.

Do I have to eat high amounts of fat to be in ketosis?

No. While fat is the primary fuel source in ketosis, that fat can come from your own stored body fat or from the food you eat. High dietary fat is only necessary if you are at your ideal weight and trying to maintain it, or if you are following a strict therapeutic protocol.

What is the carbohydrate threshold for nutritional ketosis?

Clinically, a 'very low-carbohydrate' or ketogenic diet is defined as containing 20 to 50 grams of carbohydrates per day, or roughly 10% of total daily energy intake.

The Keto Myth: It's Not All About Fat

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Note: This article was originally posted on January 4, 2021, and was updated and reviewed on April 24, 2026.

Practitioner’s Preface

The myth persists that a “keto” diet followed for weight loss or improved metabolic health is all about the fat…bacon, heavy whipping cream, and fat bombs. It’s about adding butter and MCT oil to coffee, about eating fatty cuts of meat, and lots of avocado.

It isn’t.

What makes a diet “low carb” or “keto” is only how little carbohydrate it contains, NOT how much fat it contains.

[Please note that therapeutic ketogenic diets are different from keto diets followed for weight loss and improved metabolic health.]

Defining “Low Carb” and “Keto” Diets

Different individuals and groups define ”low carb” and ”keto” (very low carb) in various ways. Feinman et al [1] defined three categories of reduced-carbohydrate diets:

(a) very low carbohydrate / ketogenic diet: carbohydrate limited to 20—50 g per day or < 10% of total energy intake
(b) low-carbohydrate diet: carbohydrate limited to < 130 g per day or < 26% of total energy intake
(c) moderate carbohydrate diet: carbohydrate limited to 130—225 g per day or 26—45% of total energy intake.

In its Consensus Report of April 18, 2019, the American Diabetes Association (ADA) and the European Association for the Study of Diabetes (EASD) defined a very low-carbohydrate (ketogenic) diet as 20-50 g carbs per day [2]. Diabetes Canada defines a very low-carbohydrate (ketogenic) diet as <50 g of carbohydrate per day [3].

What defines a low-carbohydrate or very low-carbohydrate (“keto”) diet is ONLY the amount of carbohydrate it contains. There isn’t even any mention of how much fat it contains!

How Much Carbohydrate is Essential in the Diet?

The Dietary Reference Intakes (2005), which form the basis for dietary recommendations in both the US and Canada, reads:

[Image of carbohydrate metabolism pathways]

”The lower limit of dietary carbohydrate compatible with life apparently is zero, provided that adequate amounts of protein and fat are consumed [4].”

There are essential amino acids and essential fatty acids that we need to take in through the diet, but there is no essential carbohydrate because the body can make any carbohydrate it needs from protein or fat.

How Much Fat in a Keto Diet?

There is nothing magical or mystical about how much fat or protein is required in a “low carb” or “keto” diet. Whether one starts a low-carb diet at 130 g of carbohydrate per day or a “keto” diet of 20-50 g carbohydrate per day, the remainder of daily calories is provided as protein and fat.

As outlined below, the popularized “keto” diet sets the amount of fat at approximately 75% of daily calories, but this is only one type of “keto” diet. It is a misconception that to be a “keto” diet, most of the daily calories need to be from fat.

Popularized Keto vs. Clinical Reality

The popularized “keto” diet promoted widely on the internet is described as 75% fat, 15% protein and 10% carbohydrate, but is only ONE “keto diet” and not “THE keto diet.” There are other “keto” diets, including the low-carb, high-protein, moderate-fat ketogenic diet called Protein Power [5], and the New Atkins For a New You [6].

Phinney and Volek’s approach [7] has established protein intake at up to 30% of calories during weight loss, with fat at 60%—this is NOT the same as the 75% fat of the popularized “keto” diet based largely on the work of Dr. Jason Fung [8,9] and Dr. Andreas Eenfeldt [10].

Defining “High Fat”

In the US and Canada, the recommendation has been to limit fat to 20-35% of daily calories. By definition, diets higher than 30% fat (US) or 35% fat (Canada) are considered “high fat”. A “keto” diet, which is only 40% fat, would be considered “high fat” by the USDA and Health Canada, as would a diet that is 75% fat. Interestingly, from 1949 until 1977, dietary intake in Canada was already at ~40-50% of daily calories as fat.

Clinical Applications

A “low carb” or “keto” diet is ONLY about how little carbohydrate it has (<130 g or 20-50 g per day) and has absolutely nothing to do with how much fat it has. Each individual’s macro needs are different and vary depending on age, gender, and health conditions. There is no one-size-fits-all formula; it depends on what one is seeking to accomplish.

More Info?

I would be glad to support your health through any one of the several versions of a keto diet. You can view the details of the Comprehensive Dietary Package and learn about me here.

To your good health!

Joy

You can follow me on:

Twitter: https://twitter.com/jyerdile
Facebook: https://www.facebook.com/BetterByDesignNutrition/

References

Feinman RD, Pogozelski WK, Astrup A, et al. Dietary Carbohydrate Restriction as the First Approach in Diabetes Management: critical review and evidence base. Nutrition. 2015 Jan;31(1):1-13. [https://pubmed.ncbi.nlm.nih.gov/25287761/]
Evert AB, Dennison M, Gardner CD, et al. Nutrition Therapy for Adults With Diabetes or Prediabetes: A Consensus Report. Diabetes Care. 2019 May;42(5):731-754. [https://doi.org/10.2337/dci19-0014]
Diabetes Canada. Diabetes Canada Position Statement on Low Carbohydrate Diets for Adults with Diabetes: A Rapid Review. Canadian Journal of Diabetes. 2020 Jun;44(4):295-299. [https://doi.org/10.1016/j.jcjd.2020.04.001]
National Academies of Sciences, Engineering, and Medicine. Dietary Reference Intakes for Energy, Carbohydrate, Fiber, Fat, Fatty Acids, Cholesterol, Protein, and Amino Acids. The National Academies Press. 2005. [https://doi.org/10.17226/10490]
Eades M, Eades MD. Protein Power: The High-Protein/Low-Carbohydrate Way to Lose Weight, Feel Fit, and Boost Your Health—in Just Weeks! Bantam. 1997.
Westman E, Phinney SD, Volek J. The New Atkins for a New You: The Ultimate Diet for Shedding Weight and Feeling Great. Atria Books. 2010.
Volek JS, Phinney SD. The Art and Science of Low Carbohydrate Living: An Expert Guide. Beyond Obesity LLC. 2011.
Fung J. The Obesity Code: Unlocking the Secrets of Weight Loss. Greystone Books. 2016.
Fung J, Moore J. The Complete Guide to Fasting. Victory Belt Publishing. 2016.
Eenfeldt A. Low Carb, High Fat Food Revolution. Skyhorse Publishing. 2017.

LEGAL NOTICE: The contents of this blog, including text, images, and cited statistics, are for informational purposes only. The content is not intended to be a substitute for professional medical advice, diagnosis, or treatment. Always seek the advice of your physician or other qualified health provider with any questions you may have regarding a medical condition. Never disregard professional medical advice or delay in seeking it because of something you have read in this content.

Joy Erdile, MSc, RD

I am a Registered Dietitian Nutritionist and the owner of BetterByDesign Nutrition Ltd. With a postgraduate degree in Human Nutrition and a background as a published mental health nutrition researcher, I have been dedicated to supporting my clients’ clinical needs since 2008.

I hold active professional licenses in BC (CHPBC), Alberta (CDA), and Ontario (CDO), allowing me to provide regulated Medical Nutrition Therapy across these provinces. My expertise spans chronic disease management, complex digestive health, and therapeutic diets. I am deeply passionate about helping people reclaim their health, rooted in my firm belief that Nutrition is BetterByDesign©.