I had a number of thoughts while reading this article, but I'm going to refrain from commenting for a little bit, since I'm wondering what others here think and don't want to 'bias the sample'. chuckles.
We already knew that high sugar consumption when not consuming excess calories isn't as bad as high sugar when you're in net caloric surplus. In the former, sugar isn't an addictive substance adding to the surplus but a caloric filler. That's not the case in the U.S.
Having said that you have to read between the lines of the research data. The Hadza of Tanazania are very lean and skinny people, closely related to the Ethiopians who regularly dominate distance running. Their natural leanness is reflected in their BMI of 20.2-20.4 when they're consuming sugar NOT as part of excess total calories.
The Kuna of Panama would also be naturally lean (as would all indigenous peoples). However, physiologically, the Kuna would have shorter arms and legs, thus their BMI, if truly normal, should be even lower than those with a longer torso. In other words, their BMI of 22.6 is a tad high when considering their natural squattiness. Could it be that this possibly reflects their consumption of sugar in the context of excess calories?
My educated guess is that the Kuna would resemble the skinny-fat diabetic model frequently seen in East Asia: that is, Type 2 diabetics that are skinny as opposed to fat. If so, I would be curious whether they're indeed metabolically healthy, given that they tend to be getting a bit chubby for their own good with their consumption of sugar and vegetable oils. The trouble is, you will never know because they may not be overtly obese by Western standards.
I think the point he's trying to make is that high sugar consumption on its own isn't enough to cause obesity, even though it clearly plays a role in the fattening effect seen on the SAD and other western diets.
I like Stephan's blog a lot, though I didn't love the logic in this posting. I don't think there is anything that on its own is enough to cause obesity. Refined sugar is bad, but of course if everything else in your life (rest of diet, activity, stress, sleep, etc) is done well, then the refined sugar won't make you obese. That doesn't mean the sugar isn't bad.
We're allowed to have opinions. Forming them based on what others think is a form of group-think. Post what you believe without worrying about whether or not others will agree. :)
That said, here are my thoughts: modern bleached and refined sugar is probably not the same as that from honey or fruit. There are differences in sucrose where the glucose and fructose molecules are bound vs free versions of them.
There are also other micronutrients/minerals as well as fiber in the natural versions that are not present in processed food-like-industrial-products. Speaking of which, they probably don't get much exposure to obesogens, xenoestrogens, antibiotics from CAFO meat, "natural" and artificial flavors, and so on.
Their n3/n6 ratios are likely far more ideal than ours. I doubt they've ever seen a soy bean, let a lone consumed "vegetable oil" or canola.
They also probably don't have chlorinated/fluoride polluted water, and they get plenty of minerals from their water. Nor are they exposed to diesel and gasoline exhaust, factory exhaust, and so forth.
And likely they don't consume grains, and if they do, it's not the modern, short wheat. They almost certainly won't consume GMO plants as those require a lot of pesticides and care to get grown.
They most certainly do not snack of fake-cheese flavored GMO corn chips/GMO potato chips (or Cordain-forbid GMO soy "nuts") fried in canola/soy very few hours, nor "energy" drinks or 5-6 48oz sodas/day.
They also more than likely get far more exercise and sunlight than we do.
So I'd tend to agree that "sugar" is likely not the cause of modern issues, but the sugar they consume and the sugar we consume are different, and that might be the problem, or it might be all the other stuff.
IMO the key point is here: "these cultures offer us a template for avoiding obesity and metabolic disease."
So these completely non-industrial non-neolithic food diets including lots of fruits are fine if you are active (lots of walking etc) and have not already damaged your metabolism. Once you have a damaged metabolism as many of us who have grown up on any thing but an HG diet have, large quantities of fruit aren't so good. We've broken our ability to process sugars, even from natural fruits, and it's no longer about avoiding as much as fixing obesity and metabolic disease.