In the UK things are slightly easier. The word "dietician" is reserved. It is illegal to call yourself a dietician unless you have specific qualifications and are registered.

Anyone can call themselves a nutritionist. I could set up shop tomorrow, calling myself a nutritionist.

That's made a bit more complex because you have sensible nutritionists working within public health doing real science, and you have wingnuts.

The word 'dietitian' is protected similarly in the United States, and the word 'nutritionist' is similarly unprotected.

In this case, Lustig is a professor at a major medical school and is the director of a university clinic that focuses on obesity. He has also done substantial published research in the area. In comparison Aragon's only formal credential is a master's from an unspecified university. So if we're going purely on credentials, I think Lustig wins.

I would go with: Bio PHD > MD > Masters in Nutrition

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.

A good reason why lustig spends much of his talk discussing the chemistry of sugar metabolism.