Introduction
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 forms 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 daily calories needs to be as 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.
Clarifying Definitions
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-sized-fits-all formula; it depends on what one is seeking to accomplish.
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Joy
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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.
© 2025 BetterByDesign Nutrition Ltd.
Joy Erdile is the Registered Dietitian at BetterByDesign Nutrition Ltd., and has been supporting clients’ nutritional needs since 2008. Joy has a post graduate degree in Human Nutirion, more than 17 years of experience in private practice, and is a published in mental health nutrition. She is licensed in BC, Alberta, and Ontario, and her areas of expertise range from routine to clinically complex cases. Joy is passionate about helping people feel better and restore their health, and believes that there is no one-size-fits-all approach, but that Nutrition is BetterByDesign©.