The health threat from fructose is liver damage, and all the knock-on results of a sick liver, what they call Fatty Liver Disease, Metabolic Disorder, or lately Processed Food Disease. It differs little from the cirrhosis alcoholics get.
No, they truly cannot be, at least relative to the equivalent non-obese state. (I assume, of course, a sane definition for the term "obese").
I realize this has somehow (bizarrely) become a controversial issue in the US of late but the mountain of scientific evidence is incredibly clear on this point.
It is overwhelmingly worse to have metabolic disorder without obesity than to have obesity without metabolic disorder. Many, many non-obese Americans have metabolic disorder. A smaller number are obese without metabolic disorder.
As a matter of public health, attention is much better directed to metabolic syndrome and circulatory disease, which are more responsive to interventions. Obesity draws attention because it is easily visible, and because people have attached a moral stigma to it. Blinkered public policy has led to there being overwhelmingly more obese people than the natural rate; fix policy, and the rate would return to its normal level.
And your snark of "if you don't get it" is absolutely uncalled for here on HN. It's not appropriate.
What is not proven? That people gain weight when they consume more calories than they burn? That hunter/gatherers burn more calories than people sitting at a desk most of the day? That extra nutrient absorption might help active people?
https://journals.plos.org/plosone/article?id=10.1371/journal...
“average daily energy expenditure of traditional Hadza foragers was no different than that of Westerners after controlling for body size”
(2) https://www.angelesinstitute.edu/thenightingale/daily-sugar-...
By (1), 20% of a 2000 cal diet (assumption) would be 400 cal, or 100g sugar. By (2), average US sugar intake is 71.14g/day