steveo73 wrote: ↑
Thu Mar 05, 2020 3:01 am
Nutritional science is more about we know this and it's proven.
This is not true. We can do our best to conduct studies, but in reliability these studies are second to probably only psychology. There are many, many problems with data collection in nutrition science which make this level of cetrainty-in-appeal-to-science unjustified. I am not arguing for the dismissal of the studies but for recognizing their inherent limitations. Namely:
- you depend on self-reporting, and people are notoriously imprecise when they self-report. Even when they don't deliberately lie to you, they often lie to themselves and remember having eaten much less and much healthier than they did (there was a study comparing self-reporting with pictures people took of their food). People forget snacks, estimate quantities bad, etc. etc.
- nutritional studies are some of the worst offenders when it comes to compliance. When you tell people to eat in a certain way for a certain amount of time, well, we all know how this turns out. The only way to make sure people actually eat what you tell them to eat is to feed it to them, and that is only possible over short time periods.
- You cannot conduct double-blind studies. Also, because of the ethical issues, you cannot tell people, "ok, please eat mcdonalds for a year so we can compare you with this healthy eater here" - the supersize me guy was an outlier for a reason.
- Even if you collect observational data, there are always interactions in the variables. For example, I do well eating meat. Is this because I also exercise? Or is it because of the timing of my meals? The relative sizing of my meals? My "recreational substance" consumption, which I may or may not tell you about? It's notoriously difficult to isolate what causes what. E.g. in the "eggs are bad for you" example - always? in all quantities? in all frequencies of consumption? in all combinations with other foods? under all demands on your organism/pre-existing health conditions? etc etc etc.
These are only some examples. They're not meant to justify an argument along the lines of "well, there's nothing we can know for sure, might as well burn coal; besides humans can't do anything to the planet cause god said in revelations he has a plan." The fact that you should consume food that isn't processed and in moderate amounts and that you should stay away from industrial chemistry masquerading as potato chips and oreo cookies isn't up for debate. But we are limited in the certainty with which we can insist on It'S sCiEnCe!!!!11!! when it comes to nutrition. It isn't science, it's just our best guess. Might take a whole cohort getting heart disease from the trans fats in margarine to figure out that we've guessed wrong.