I was surprised to read a discussion on social media today which said that the Diet Doctor website recommended that low carbohydrate meal plans be up to 100g of carbohydrate per day, rather than using the generally accepted definition from Feinman et al  which defines low carbohydrate < 130g carbohydrate / day.
Feinman et al  define very low carbohydrate (“keto”) diet, low carbohydrate diet and moderate carbohydrate diet as follows:
1. very low carbohydrate (keto) diet: 20–50g carbohydrate /day, < 10% total energy intake
2. low carbohydrate diet: < 130g carbohydrate / day, < 26% of total energy intake
3. moderate carbohydrate diet: 130–225g carbohydrate / day, 26–45% of total energy intake
The above definitions have been used by Diabetes Associations around the world, including the American Diabetes Association, the European Association for the Study of Diabetes (EASD), Diabetes Australia, and Diabetes Canada.
The American Diabetes Association in conjunction with the European Association for the Study of Diabetes (EASD) used the above definition of a low carbohydrate diet and very low carbohydrate diet in their joint 2019 Consensus Report  and the American Diabetes Association used the same definition in their 2020 Standards of Medical Care in Diabetes .
The same definition for a low carbohydrate diet and moderate carbohydrate diet were also used by Diabetes Australia in their 2018 Position Statement on Low Carbohydrate Eating for People with Diabetes .
Diabetes Canada in their 2020 Position Statement on Low Carbohydrate Diets for Adults with Diabetes also defined a very low carbohydrate diets as < 50 g of carbohydrate per day and a low carbohydrate diet as 51 – 130 g of carbohydrate per day .
Given that the definitions for low carbohydrate and very low carbohydrate (“keto”) are widely accepted, why define a low carbohydrate meal plan as “up to 100 grams of carbs per day”?
Why does it matter?
Why a Standard Definition of a “Low Carbohydrate” Diet Matters
It matters whether there is a standard definition because otherwise there is no standard in the marketplace or in research for what “low carbohydrate” is.
There are hundreds, if not thousands of “low carb” products available on the market and none of these are held to any standard as to what makes them suitable for individuals following a low carbohydrate or very low carbohydrate (“keto”) diets. The terms “low carb” or “keto” on product labels are meaningless! Without a standard definition, it is up to each consumer to read the label and try to determine if these products are suitable.
A Nutrient Content Claim characterizes the level of a nutrient in a food, so terms like “low-fat” have specific nutritional thresholds and nutrition content claims made on labels are regulated by law. At present, there are no nutrient thresholds for carbohydrate content — and these are needed.
Adopting Feinman et al’s widely used definitions makes sense and will make it possible to for the consume to be provided with meaningful labels, enabling the average consumer to know if a product is suitable for their needs, or not.
Scientific Research Requires a Standard Definition for “Low Carbohydrate”
Without a standard definition for “low carbohydrate < 130g carbohydrate / day”, research studies can define “low carbohydrate” anyway they want — which also means that conclusions of studies can state that “a low carbohydrate diet is associated with increased mortality (death)” when the diet used in the study was well over 130 g of carbohydrate per day”.
In fact, this is exactly what has been occurring.
Dr. Sarah Hallberg, Medical Director at Virta Health said it best on Twitter April 20, 2021;
“Honest representation of evidence is important. How many people have heard someone say that a low carb diet is associated with increased mortality? There is no evidence for this. Here are all the studies that make that claim. None were actually low carb. Much closer to SAD [Standard American Diet].
Let’s have a closer look at the studies Dr. Hallberg cited.
The above 10 studies were said to associate “low carbohydrate diets” with increased mortality, however none of the studies were actually “low carbohydrate”, as defined by Feinman et al .
The average carbohydrate intake in these studies were 41.34% —not a low carbohydrate diet which is < 26% of total energy intake . These studies were moderate carbohydrate diet, using Feinman et al’s definition.
The range of carbohydrate intake in these studies was 36.2 % – 51.5 % /day — which means even the study with the lowest carbohydrate intake exceeded the cut-off of a low carbohydrate diet of < 26% of total energy intake, defined by Feinman et al .
When the media circulates reports that “a low carb diet is associated with increased mortality” it is imperative that “low carb” is defined as <130 g carbohydrate per day. Otherwise what the message that the public receives is that these diets are dangerous, when the diet used in the study wasn’t a low carbohydrate diet at all!
We need to get our terms straight.
We need to be consistent.
Feinman et al’s definition of “low carbohydrate” and “very low carbohydrate” / “keto” have already been adopted by Diabetes Associations around the world, including the American Diabetes Association, the European Association for the Study of Diabetes (EASD), Diabetes Australia, and Diabetes Canada.
Let’s use them.
Let’s lobby our governments to require them to be used on product labels to provide honesty and accuracy in labelling.
Let’s push for academic institutions and scientific publications to adopt these definitions as standard, so that research has meaning — and conclusions to not mislead people to believing something is dangerous, when the thing that was studies was something different.
If you would like to know more about the low carbohydrate (<130g carbs / day) and very low carbohydrate (“keto”) services I provide (< 50 g carbs / day), please have a look under the Services tab, above.
To your good health!
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NOTE: This article was inspired by important discussion on Twitter between Antonio Martinez II and Nina Teicholz, which included the post above from Dr. Sarah Hallberg.
- 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
- A Consensus Report, Diabetes Care, Ahead of Print, published online April 18, 2019, https://doi.org/10.2337/dci19-0014
- American Diabetes Association, Facilitating Behavior Change and Well-being to Improve Health Outcomes: Standards of Medical Care in Diabetes—2020
- Diabetes Australia, Position Statement – Low Carbohydrate Eating for People with Diabetes, August 2018, https://www.diabetesaustralia.com.au/wp-content/uploads/Diabetes-Australia-Position-Statement-Low-Carb-Eating.pdf
- 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.
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