The Kitavans eat large amounts of starch. Some populations probably ate a lot of fruit. SOme populations drank tons of milk. European populations have eaten bread for quite some time. Yet now we are suddenly all getting so very much sicker as populations. So where lies the threshold? Obviously, there will be individual variations but our population in general seems well past the threshold now. But at what point does the human system become so overwhelmed that we go from sometimes eating things that may not be ideal healthwise to just being sick animals all the time. Does it take a multitude of factors like sugar plus starch plus high fructose corn syrup plus grains plus grain oils or could one or two factors alone have done the job? Has any population been done in by just one of these factors or does it take more than one? At what point do unhealthful factors shift a population from being mostly healthy to mostly unhealthy?
Cheap food abundance. Bread, sugar, and oil have been around longer than the obesity epidemic. Cheap access to those items is a recent phenomenon. Give a human (or a lab rat) unlimited access to inexpensive sweet and salty foods, and our meager brains cannot forecast the ills that will occur.
Heck, I had a bad day the other day, and ate a big bag of cheeseballs, eight donuts, and four Reese's peanut butter cups. And I sure as heck know how bad those foods are. But sugar is an amazing drug!
And I doubt that there were many cultures that were as healthy as we commonly think. We are largely missing some big downers now a days: smallpox, cholera, TB, Spanish Flu, etc etc. Even a morbidly obese diabetic with a quadruple bypass has a chance of leading a happy life because of surgery and drugs. Cholera sufferer in the 1800's? Unfortunately doomed to a sad life.
Starch is not wheat or fructose. Starch is not associated with disease except as a loose carb association
Plenty of cultures have thrived on starch, Kitivans, Okinowans, even the Irish thrived on a potato diet.
Which cultures were healthy on large amounts of fruit?
Fructose in modern amounts is very new. Grains in modern amounts are very new. Oxidized Vegetable Oil is very new.
To complement Stephen-Aegis's reply,
A change in disease classification can counfound any retrospective analysis because it introduces a confounding variables. For example, Taubes noted in Good Carbs, Bad Carbs, that part of the reported increase in cardiovascular deaths in the early to mid 20th century was due to the refinement of diagnostic tools like the EKG.
Still, I think changing classifications only obscure the underlying problem that Stephen noted- our technological prowess has had significant physiologcal collateral damage.
It might all come down to processing:
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