[themk]

That is quite an extreme take, and one that sounds like it was born from parroting social media takes. Ancel Keys was largely correct, and much of what he said is corroborated by modern science. Probably his main issue was that he was a bit too focused on saturated fat, which is not wrong, but not the only factor. He was wrong that sugar is just empty calories, though he never recommended replacing fat with sugar.

Modern science agrees that saturated fats lead to CVD, but replacing saturated fats with refined carbs also leads to CVD, which Ancel Keys didn't believe (though, to be fair, the populations he studied didn't have access to the types of refined carbohydrates we have today)

The dietary guidelines derived from his work did backfire, but Keys never said to replace saturated fats with refined carbs, which is what ended up happening. He advocated for substituting different fats. But the message that ended up being received was "no fat at all", which no scientist ever actually recommended AFAIU.

The diet he actually recommends is well studied, and found to be protective.