The problem with "nutrition experts" is that most are taught the same misinformation that is taught to med students on their way to getting their MDs.
So the view of the experts is one based on a lack of knowledge in their own field.
Lack of long-term data? What about the fact that humans still exist? Research has shown that early humans ate mostly protein and fat--and very little carbohydrate. In fact, the percentage of carbohydrate on the planet that is digestible by humans is very small. The "ketogenic diet" was just how early humans ate... Humans evolved to what we are today BECAUSE we eat protein and fat. Carbohydrate is a staple part of our current diet--but for 99.995% of human history, this was not the case.
Our digestive system evolved in a low-carb environment.
The U.S. Department of Health and Human Services and U.S. Department of Agriculture 2015–2020: The Dietary Guidelines for Americans. 8th edition. (p91) defines an Essential Nutrient as “A vitamin, mineral, fatty acid, or amino acid required for normal body functioning that either cannot be synthesized by the body at all, or cannot be synthesized in amounts adequate for good health, and thus must be obtained from a dietary source.” In other words, “essential nutrients” are defined as nutrients we need to eat to allow our bodies to function normally.
Note, they do not mention carbohydrate in their list of essential nutrients. This is not an error on their part.
While we need glucose, and glucose CAN be derived from carbohydrate, we don't need to eat carbs to get glucose. Why? Because our liver will convert fat into glucose through a process called gluconeogenesis.
In fact, in 2005, the Panel on Macronutrients: Dietary Reference Intakes for Energy, Carbohydrate, Fiber, Fat, Fatty Acids, Cholesterol, Protein, and Amino Acids (Macronutrients) concluded “The lower limit of dietary carbohydrate apparently is zero, provided that adequate amounts of protein and fat are consumed.” You can see, by the fact that they added the word “apparently” in their report, that they were surprised by this finding as well!
A diet of zero grams of carbs per day will put one into ketosis--and will cause no adverse impact on most people.
The food industry is a big backer (financially) of nutrition schools, textbooks, journals and nutrition research. It is in their best interest (as an industry() to keep people eating the carb-rich foods they make. These companies have a responsibility to make money for investors--not keep the population healthy.
It's funny how they say they look at how the diets impact MOST people, then point out tiny segments of the population that will have trouble with it--or any diet, for that matter.
I've been eating various levels of low-carb for 10 years (most of that time I didn't even realize I was doing it--I was on a point-system and I found I could eat more food if I had less carbs!). I've lost 175 pounds--kept it off--and all my health markers are perfect--according to my doctor.