I'll admit that I'm biased, because my wife has a PhD in nutrition (as well as being a registered dietitian), but my best friend from high school is now an MD, and my wife knows more about nutrition and its effect on the body than he does.

Also, I'm aware that's merely an anecdote. Based on purely empirical evidence, I'd place both my wife and my friend in the top 10% of their respective fields, though.

Though of course, if the sugar question was a settled question in nutrition science, this thread wouldn't be happening, so comparing credentials isn't really relevant to the sugar question.

I disagree.

The sugar question is settled in nutrition science. Sugar that doesn't occur naturally in food is pretty bad for you. But underqualified people have different opinions and get a disproportionate amount of face time on media.

In fact, I'd say the question is almost identical to the climate change 'debate'. The science is settled, but the average American doesn't know who to believe.

How can something be merely anecdotal and empirically evidenced at the same time?

You've misread his comment.

The comparison of his wife and best friend is the anecdote.

He then adds separately that he has empirical evidence--unshared with us--that each is competent in their respective fields.

He doesn't claim anything to be simultaneously an anecdote and empirical evidence.