People on social media argue about which is the “best diet” for humans — vegan or carnivore? Low carb or keto? Vegetarian or vegan? I avoid these “diet wars” largely because I don’t believe there is a “best” diet for everybody. Some diets are preferable over others for a variety of reasons, including religious constraints, ethical reasons and specific health conditions — so the “best diet” is one that meets an individual’s personal health goals and objectives, and that is consistent with their belief system.
One of my clients recently mentioned that the more they read about different types of diets online, the more confused they became. They wanted to know if I could write an article to explain them simply. That is the purpose of this post.
Foods are made up of protein, fat and carbohydrate in different ratios, and these together are commonly referred to as “macros“. This term is shortened from “macronutrients“, where macro means “big” in Greek. Micronutrients is the term used for all the vitamins and minerals, where micro means “small” in Greek.
Macros refer to the three categories of nutrients (protein, carbohydrates and fat) that make up the food that people eat, and which together provide them with their source of energy, as calories.
When people are “counting macros” or “calculating their macros”, they are counting the grams of proteins, carbohydrate (carbs) and fat they are eating.
Different Diet Types
This is not an exhaustive list of all the different diet types, but a summary of popular categories.
Standard American Diet
The average American (or Canadian diet) is often referred to as the “SAD Diet” — which is a shortened form of the “Standard American Diet“.
The Standard American Diet is one where the majority of calories come from carbohydrate and fat — mostly vegetable fat, as recommended by both the American and Canadian dietary guidelines. Vegetable fats are also called “seed oils” and include soybean, canola, and corn oil.
Carbohydrate (“carbs”) are most commonly thought of in terms of various types of bread, rolls, pizza, pasta, rice, and potatoes (French fries, mashed, baked potato, boiled potato), but also include fruit (other than berries which are eaten on a low carb diet), as well as fruit juice, and milk (but not cheese or yogurt that are low in carbs). Milk is included as “carbs” because of its high carbohydrate content.
Vegetarians and Vegans
Vegetarians are those that don’t eat meat, fish or poultry, but do eat eggs and milk. These are also known as ovo-lacto vegetarians, as they eat eggs (“ovo” meaning eggs) and milk (“lacto” meaning milk).
Pescatarians are vegetarians that eat fish.
People who eat a vegetarian or pescatarian diet can also eat low carb or very low carb (keto). They are not mutually exclusive.
Vegans don’t eat any food of animal origin, including eggs, milk, butter or cream (and products made from them) may do so for religious or ethical reasons. Vegans are sometimes considered a subclass of vegetarian, or an entirely different category.
They often refer to themselves eating an entirely “plant-based” diet.
A vegan diet can be done low carb, but to obtain adequate nutrients takes a great deal of time and knowledge, but it can be done.
“Low Carb” – LCHF
In a research context  and in the clinical guidelines of the American Diabetes Association  and Diabetes Canada , low carbohydrate diets (“low carb”) are those where carbohydrate intake is limited to <130 g per day or < 26% of total energy intake.
These are also referred to as low carb high fat diets (LCHF) or low carb healthy fat diets (also LCHF).
Moderate carbohydrate diets are where carbohydrate intake is limited to 130–225 g per day or 26–45% of total energy intake .
A “Paleo diet” is modelled after what is understood to have been the diet of our ancient hunter-gatherer ancestors. It varies considerably between individuals, but is essentially a low carbohydrate diet that uses protein and fat sources that have been known to mankind for millennia.
A Keto Diet
A keto diet is a subtype of low carb diet and in a research context , and in the clinical guidelines of the American Diabetes Association  and Diabetes Canada  are referred to as “very low carbohydrate diets“. A “very low carbohydrate diet”, or “keto diet” is one where carbohydrate intake is limited to 20-50 g per day or 10% of total energy intake [1,2,3].
They are called “keto” diets because at this very low level of carbohydrate intake, blood ketones (by-products of the body burning fat for energy) increase at or above 0.5 mmol/L, resulting in a state known as “ketosis”.
Keto diets used predominantly for weight loss or improving symptoms of type 2 diabetes are where ketone levels are usually set with betahydroxybutyrate (BHB) levels between 1.5-3.0 mmol/L .
There is no one “keto diet” but some versions of the popularized high fat keto diet are associated with Dr. Jason Fung and Diet Doctor.
Therapeutic Ketogenic Diet
The first therapeutic ketogenic diet was used in the 1920s by Dr. Russell Wilder, for the treatment of diabetes and later, for epilepsy.
The percentage of carbohydrate, fat and protein in what has since become called the “classic” Ketogenic Diet (KD) was worked out by Dr. M.G. Peterman in 1925 , and are the same as used today.
In the classic KD, the total amount of calories are matched to the number of calories the person needs. Protein is usually determined as being 1 g of protein per kg body weight, 10-15 g of carbohydrate per day total, and the remainder of calories provided as fat. For very young children, the diet may be prescribed based on body weight (e.g. 75-100 calories for each kg (2.2 pounds) of body weight.
Since the 1920s, several other therapeutic ketogenic for the treatment of epilepsy and seizure disorder have been developed, including the Modified Ketogenic Diet (MKD) and the Modified Atkins Diet (MAD). They are all very low carbohydrate diets high fat diets which is by definition what makes them ketogenic, differ in the amount of protein they contain.
As well as their use in epilepsy and seizure disorder, any of the above therapeutic ketogenic diets may be prescribed for patients as adjunct treatment in glioblastoma, or as adjunct treatment in Alzheimer’s disease.
The classic Ketogenic Diet (KD) has a 4:1 ratio i.e. 4 parts of fat for every 1 part protein and carbs. That is, for every 5 grams of food there are 4 grams of fat and 1 gram of protein and/or carbohydrate.
In the classic Ketogenic Diet, 80% (i.e. 4÷5=80%) of calories come from fat and 20% (i.e. 1÷5=20%) from a combination of protein and carbohydrate.
Protein may be set at 15% of calories with a maximum of 5% of calories coming from carbohydrate, or protein may be set lower at 10%, and carbohydrate as high as 10%.
The Modified Ketogenic Diet (MKD) has a 3:1 ratio i.e. 3 parts fat for every 1-part protein and carbohydrate. In a Modified Ketogenic Diet, 75% of calories come from fat and 25% from a combination of protein and carbohydrate. Protein may be set at 15% of calories with a maximum of 10% of calories coming from carbohydrate.
The Modified Atkins Diet (MAD) has a 2:1 ratio, with 2 parts fat for every 1-part protein and carbohydrate. In a Modified Atkins Diet, carbohydrates are restricted to <15 g / day for children, <20 g / day for adults. In a Modified Atkins Diet for adults, 60% of calories come from fat, 30% of calories come from protein, and 10% of calories come from carbohydrate.
These high fat diets are not weight loss diets. These are therapeutic ketogenic diets used with the goal of producing high amounts of ketones (> 4.0 mmol/L / 40 mg/dl) for therapeutic reasons.
Carnivores are people who eat only protein and fat of animal origin, including any edible part of mammals (including organ meats), birds of many types including poultry such as chicken and turkey as well as their eggs, and fish and seafood. Fats include butter, rendered chicken or duck fat, beef fat (tallow), and lard (rendered pig fat).
Carnivores and vegans are polar opposites — one eating ONLY animal products and the other not eating any animal products.
Protein to Energy (P:E)
Protein to Energy (P:E) is an entirely new class of diet created by Dr. Ted Naiman. It focusses on eating the most amount of protein for the least amount of energy (calories).
It is not a low carbohydrate diet as the P:E calculator recommend carbohydrate intake >130 g per day, which is the cut-off for low carb in most of the literature.
This article explains how everyone’s protein needs are different, and how protein should be calculated to prevent deficiency, to sustain exercise and to preserve muscle mass in older adults. Each of these calculations are different but at the same time, total protein should not exceed the ability of the kidney to excrete urea.
There is no “best diet” for everyone. The “best diet” is an individual is one that meets their personal health goals and objectives and that is consistent with their beliefs.
If you would like more information about my services, please have a look around my web page and if you have questions, please send me a note through the Contact Me form.
To your good health!
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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.
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