It is also settled evolutionary science and paleontology that we humans, during our entire evolution of hundreds of thousands of years, did not eat a lot of meat until very recently. We are not evolved to eat paleo, keto, or carnivore long term and they are damaging.
Science paints another story. We can determine how much meat we ate from the rate of some nitrogen isotopes in bones. Hunters and gatherers got about 65% of their calories from animal sources, while we got only 20% or less calories from carbs on average.
https://www.nature.com/articles/1601353
https://pubmed.ncbi.nlm.nih.gov/19706482/
https://pubmed.ncbi.nlm.nih.gov/21745624/
You said there are no long-term studies. This is not entirely true. There are several long-term studies that were supposed to show that a low-meat, low-fat diet is good and prevents certain diseases. ALL THOSE STUDIES FAILED and are curiously absent in modern nutritional advice. Studies like Womens Health yielded no change at all, while studies like MRFIT clearly showed increased overall mortality in the group that switched to low-fat/low saturated fat diet (especially the followup study a few years later). We saw higher rates of cancer, depression, diabetes and whatnot in the high-carb group. And these were among the most expensive nutrition studies to be conducted ever, MRFIT cost 150 million US$. I'd say that's pretty good evidence that the so-called "prudent" diet is detrimental to health.
We can argue about which is a good diet. Neither of us can conclusively show whether we need fiber or not, and stuff like that. And I do agree that a "good" diet is highly individual, and there is no universally "best" diet for everybody.
However, there is a diet that evolition shaped us for, the "evolutionary normal". I have yet to find any evidence that, for most people, there is a better diet than what our hunter-and-gatherer ancestors ate. And this diet is high saturated fat, high in animal protein and low in carbs. It did contain some vegetables and some starch, but in fairly limited amounts.
Paleo and keto are 2 different diets. They can overlap, but much of the time, they don't.
True. I myself eat a diet that is mostly paleo, mostly ketogenic and strictly avoids lectins, oxalates, emulsifiers and most other modern chemical ingredients (preservatives, artificial flavors and the like). But my diet was not under discussion here
As I said, this is too complex for a few paragraphs. A good diet can't be reduced to a single statement like "avoid carbs" or "avoid all modern food".
We could debate this particular topic for a very long time. I will just give you one example, and that's resveratrol.
In the end it comes down to total mortality on one side, and the treatment of specific diseases on the other side. We're getting caught up in discussions for and against certain food ingredients/supplements, but almost all of the studies fail to see the big picture.
The thing with fiber: If our ancestors ate apples, it was summer. Fructose/sugar in the apples would raise oxidative stress, but some fiber in the apples works as antioxidant, and high vitamin D from the sun would offset this effect. (Might be pectin in apples, resveratrol in grapes and something else in other fruit.) So nature provided balance, we didn't come to harm. However, if we eat a lot of sugar in winter (no vitamin D) from juice or refined sugar (no fiber), we get sick. And of course adding antioxidants will be helpful in this case. But would antioxidants do anything if we didn't consume the sugar in the first place? Do we need antioxidants if we eat only locally grown fruit in summer and autumn, or if we go carnivore?
We do need more studies, good studies. Most of the studies have been done against a baseline of a western diet, and the outcomes might be very different if we do them against a baseline of paleo or keto. And for the record, I'm not a strict keto guy. I do think that keto is the "antidote" to insulin resistance related diseases, but this does not establish that keto is good if you don't have these diseases. The evidence that I've seen is that keto works very well against specific diseases like (pre)diabetes, high blood pressure, heartburn and more. And there are plenty of doctors out there treating patients successfully with various diets in the paleo/keto family. Some doctors manage breakthrough in autoimmune diseases, depression, neuroinflammation and other diseases that are deemed incurable by traditional medicine. So there is tremendous potential here.
I'll concede that there is much more that we *don't* know than what we *do* know. But if somebody claims that paleo or keto is dangerous and will inevitably lead to heart disease and whatever other early demise, that's simply unscientific misinformation. Especially with a ME/CFS background, where issues with the PDH may cause some major carb intolerance for many of us.
