The myth persists that a “keto” diet 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.
What makes a diet “low carb” or “keto” is only how little carbohydrate it contains NOT how much fat it contains.
Defining “Low Carb” and “Keto” Diets
Different individuals and groups define “low carb” and “keto” (very low carb) in various ways. Feinman et al  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 and the European Association for the Study of Diabetes (EASD) defined a low carbohydrate diet as having 26-45% of total daily calories as carbohydrate (a combination of a low carbohydrate diet and a moderate carbohydrate diet defined by Feinman et al), and defined a very low carbohydrate (ketogenic) diet as 20-50 g carbs per day. In its 2020 Standards of Medical Care in Diabetes, the American Diabetes Association continued to define low carb and very low carb the same way.
Diabetes Canada also defines a low carbohydrate diet as less than <130 g of carbohydrate per day or <45% energy as carbohydrate, and very low carbohydrate (ketogenic) diet as <50 g of carbohydrate per day in its April 2020 Position Statement .
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 for Energy, Carbohydrate, Fiber, Fat, Fatty Acids, Cholesterol, Protein and Amino Acids (2005) which forms the basis for dietary recommendations in both the US and Canada reads;
“The lower limit of dietary carbohydrate compatible with life apparently is zero, provided that adequate amounts of protein and fat are consumed.
There are essential amino acids and essential fatty acids that we need to take in through the diet because the body can’t make these, but there is no essential carbohydrate because the body can make any carbohydrate it needs from amino acids (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 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 as fat, but this is only one type of “keto” diet.
It is a misconception is that to be a “keto” diet, most of daily calories needs to be as fat.
It is also a misconception that added fat that is part of a low carb or “keto” diet must be animal fat. Added fat as food or to cook with, or to put on salad can be provided by high fat fruit such as avocado or olives (fruit or oil), coconut (meat or oil), and nuts and seeds. If people choose, they can be low carb or “keto” and eat a predominantly whole-food plant-based (vegetarian) meal pattern.
Popularized “Keto” Diet
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 published in 1997 by Dr. Michael Eades and his wife Dr. Mary Dan Eades , the 2010 New Atkins For a New You  — which is a redesign of the original “Atkins Diet” from the 1970s written by Dr. Eric Westman, Dr. Stephen Phinney MD PhD, and Dr. Jeff Volek RD PhD which is only a very high fat ketogenic diet (20-50 g carbs per day) for phase one which lasts only the first two weeks, and there is also Real Meal Revolution  by Tim Noakes, Sally-Ann Creed, Jonno Proudfoot. Phinney and Volek’s approach in their 2011 book, the Art and Science of Low Carbohydrate Living has been to establish carbohydrate intake at 7.5-10% of calories for men, 2.5-6.5% of calories for women, protein intake at up to 30% of calories during weight loss, 21% during weight maintenance and fat intake to 60% of calories during weight loss and 65-72% during weight maintenance. Fat intake at 60% of calories during weight loss is NOT the same as the 75% calories as fat of the popularized “keto” diet.
The popularized “keto” diet is based largely on the two 2016 books by Dr. Jason Fung titled the Obesity Code  and The Complete Guide to Fasting , and the 2017 book titled by Dr. Andreas Eenfeldt, the founder of the popular “Diet Doctor website”, titled A Low Carb, High Fat Food Revolution  — both of whom write extensively on the Diet Doctor website.
Defining “High Fat”
In the US, the recommendation has been to limit calories from fat to no more than 30% of daily calories, of which no more than 1/3 comes from saturated fat and in Canada, to limit fat to 20-35% of daily calories as fat, with no more than 1/3 from saturated fat. 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 “keto” diet that is 75% fat.
But is a diet that is 40% fat really “high fat”?
From 1949 until 1977, dietary intake in Canada was at ~40-50% of daily calories as fat, ~20-30% of daily calories as protein, and only 20-30% as carbohydrate. Was this the original “low carb high fat” diet?
In anything, it is important to define terms.
A “low carb” or “keto” diet is ONLY about how little carbohydrate it has (<130 g carbohydrate per day, 20-50 g of carbohydrate per day) and has absolutely nothing to do with how much fat it has.
Or how much protein in has, for that matter.
Contrary to what some on social media want to know, there is no “protein starting point” for a low carb or “keto” diet. Each individual’s macro needs (energy, protein, fat and carbohydrate) are different, and vary depending on a person’s age, gender, stage of life, health conditions, and activity for example.
There is no one-sized-fits-all low carb or “keto” diet with a set amount of fat, and set amount of protein. It depends what one is seeking to accomplish. Based on the definition, a low carb or “keto” diet for weight loss could range from 40% fat to 75% fat — and up to 90% for those following a therapeutic ketogenic diet for seizure disorder or glioblastoma.
People are always looking for the “formula for success” when it comes to weight loss but there isn’t one, except the one that works best for them.
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- Feinman RD, Pogozelski WK, Astrup A, Bernstein RK, Fine EJ,Westman EC, et al. Dietary Carbohydrate Restriction as the First Approach in Diabetes Management: critical review and evidence base. Nutrition. 2015;31(1):1–13
- Evert, AB, Dennison M, Gardner CD, et al, Nutrition Therapy for Adults With Diabetes or Prediabetes: A Consensus Report, Diabetes Care, Ahead of Print, published online April 18, 2019, 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), doi: 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, 2005, https://www.nap.edu/catalog/10490/dietary-reference-intakes-for-energy-carbohydrate-fiber-fat-fatty-acids-cholesterol-protein-and-amino-acids
- Eades M, Dan Eades M (1997), Protein Power: The High-Protein/Low-Carbohydrate Way to Lose Weight, Feel Fit, and Boost Your Health–in Just Weeks! Bantam; New edition edition (1 December 1997)
- Westman E, Phinney SD, Volek J, (2010) The New Atkins for a New You – the Ultimate Diet for Shedding Weight and Feeling Great, Atria Books February 17, 2010)
- Volek JS, Phinney SD, The Art and Science of Low Carbohydrate Living: An Expert Guide, Beyond Obesity, 2011
- Noakes T, Creed S-A, Proudfoot J, et al, (2013)The Meal Real Revolution, Quivertree Publications
- Fung J (2016) Obesity Code, Greystone Books, Vancouver
- Fung J, Moore J (2016), The complete guide to fasting : heal your body through intermittent, alternate-day, and extended fasting, Victory Belt Publishing
- Eenfeldt A, Low Carb, High Fat Food Revolution: Advice and Recipes to Improve Your Health and Reduce Your Weight (2017), Skyhorse Publishers