They used to have no carbs in their diet. They eat lots of carbs now.
Yeah, and have massive problems because of it. Adoption of a western diet has wrought incredible damage on native health and communities. Obesity and diabetes is epidemic: over 50% in many communities. Alcoholism is endemic: over 70% is an official figure, but it is probably near-universal in all who are not absolute "tea-total" abstainers. Indigenous peoples tend to develop diabetes and they cannot metabolize alcohol - not just in Canada, but everywhere around the globe.
Think about that: carbs as a substantial part of the diet date back to the adoption of sedentary farming in ancient Sumer - present-day Iraq. Prior to that wandering hunter-gatherers would collect edible seeds from progenitors of seed crops like wheat, (ancient versions of teff, etc.). Prior to 7,000 years of selective breeding to enhance the size, number and edibility of seeds this would have been an incredibly time-consuming activity yielding very low return. We can see how low yield: this lifestyle is still practiced by a (dwindling) few of the San, the Little People of the Kalahari desert in Namibia, the last surviving natives of Africa who still make a living doing what your average human did 10,000 years ago, and for the preceding 250,000 years or however long you want to attribute to paleolithic man. And if collecting seeds was hugely unrewarding, so was collecting other carb products: root vegetables and edible leaves & fruit. In their natural, uncultivated original state, these plants are hard to harvest & frequently hard to eat, small & low-yield, and not exactly in abundance. Farming changed everything, eventually, but over thousands of years.
Farming also changed our gut: we evolved to live on a carb-rich diet. We accumulated microbes and enzymes in our guts to digest carbs. But that was a fairly recent development: academic estimates range from 5,000 to 7,000 years ago. That's as little as 200 generations for people: not a long time to evolve changes to our gut. And it shows: we still have a sizeable percentage of the population that cannot, for some reason, adapt to live on carbs, or who lose the ability to do so as they age. We call that a metabolic syndrome, or diabetes (T2D at least). Current research suggests that many related degenerative diseases (Parkinsons, Multiple Sclerosis, Alzheimers) are similarly rooted in a dysfunction of the gut lining, or of the gut biome - the ecosystem of bacteria and enzymes that live in our intestinal tract. This understanding is recent, but absolutely non-controversial.
A typical Canadian who moves north to live in the Northwest Territories, the Yukon or the Arctic will generally adopt a more-or-less modified Northern diet over time. Sure, they'll make baked goods & use tinned products, but fresh fruit & veg, dairy and especially baked goods are outrageously expensive in the north and generally **** quality: they've been in transit for extended times & suffered accordingly. Most people start hunting if game is available, and supplement bought foodstuff from the south with moose, caribou, deer, fish... whatever. If they can. Interesting thing: those who adjust to the northern diet often lose, over time, the ability to digest carbs well. If they move south again they often complain of stomach/gastro troubles, diarrhea, etc., until 4-6 months later they acquire the bacteria & enzymes required to digest breads & grain products. Not always the case, but then lots of people in the north do bake with flour, so that population would stay carb-adjusted.
So those of us with a 4,000 year history of carb-adjustment
can lose it over an extended period. But what about natives, who "did the adjustment" last week, as it were? They've had access to southern foods since 1900 at best; the 1950s for many of them. Two generations; perhaps three. No wonder they can't metabolize carbs - especially grains & grain products. And of course they can't metabolize grain alcohol either. I suggest natives aren't overwhelmingly addicted because of life circumstances, social ills, poverty or the psychological & social fallout from the appalling way they were treated last century by the rest of the population (especially those running government institutions). They're easily addicted because we yanked them out of the stone age and into a carbohydrate diet (and exposure to alcohol) in two generations, not 200. Their bodies can't cope. It isn't a social, psychological or "existential" problem, whatever they may (& do) claim: its a gastric problem, a genetic problem.
Sorry. Back to your original question:
"Is a Ketogenic diet harmful?"
Hell no. A Keto diet is what we evolved to live on for the last quarter-million years (til last Tuesday, just prior to Babylon). We do it fine. You don't need carbs in your diet.
There is no such thing as an essential carb (latest advice from the FDA agrees with that, BTW)
. The FDA-approved Food Guide of the past 70 years is bogus, based on no "scientific" research and designed to mollify every food industry that lobbies government in Washington. Can we live on carbs? Absolutely! As hunter-gatherers we were opportunistic, constantly threatened by starvation, and capable of getting by for a while by using whatever we found handy. Fruit or honey? Check. Tubers & edible roots? Check. Seeds & leaves? Check. But living ON them in the absence of animal proteins and fat? Nope. Not until we invented farming, increased the yield and modified our gut. With some success, but considerable health consequences for many of us. We only treat a carb-rich diet as "
normal' because it is
now. It is
not our 'natural state.' The good health of paleolithic natives prior to exposure to our carb-rich diet, and the relative absence of western cardio, endocrinological & neuro-degenerative diseases among them, attests to the safety of the Keto diet. (Good health not including periodic starvation & ever-present infectious diseases, of course, but that's another issue not really related to this discussion).
BTW, we have abundant medical experience with people living healthily on the Keto diet long-term. It has been known & used medically as a treatment for epilepsy since 1900, and has been widely used as treatment of choice for epileptic drug-resistant children in particular. But medicine has a much bigger problem with vertical "siloing" than industry: the tendency of each sub-specialty to ignore knowledge acquired in another, however closely related. As a result, doctors outside pediatric epilepsy wards haven't been paying attention.
So yeah, the Keto diet is safe: we've got 60 years experience watching people grow up and grow old using it to cope somewhat with epilepsy. And native communities world-wide did just fine on it for a couple hundred thousand years. You don't need fruit, grains, sugars or carbs of any kind to grow up, stay healthy, grow old. You many miss them for a while, but that's another thing altogether.
If you can cope with carbs, enjoy them. If they're killing you, wise up.