[mod]

To add: this is also why many other discussions suck: politics, economics, religion, etc.

Everyone's a fucking expert, can disregard science because [someone on tv] disagrees with peer-reviewed studies, and there's no obvious correct answer.

At least on HN it's moderately fact-based, even in disagreement. If you dare to read discussions--dare I call them that--on somewhere like Facebook or Reddit...well, godspeed.

[kedean]

Nutrition discussions suck because nobody is demonstrably wrong. It doesn't matter if you can back your opinion up with a study, because the other can can back up his contradicting opinion with another study. There are no canonical facts, because the studies are just so hard to control. We know nothing, in the end.