As a layman non-scientist, I wonder why we see so many relatively low-value observational studies in diet/nutrition, often with results that get contradicted or fail to replicate a few years later.
What would prevent us from doing a study like this: take 1000 diverse subjects, assign each of them a lab assistant, and for 2+ years, diligently track everything they eat, their exercise, sleep, etc. You could pay each participant and staff $100k/each, and the cost would be on the order of $400MM.
May not be epistemologically perfect given that people change their behavior when observed, but still superior to plenty of the stuff getting published now, and likely the knowledge gained for humankind would be worth many billions.
> As a layman non-scientist, I wonder why we see so many relatively low-value observational studies in diet/nutrition, often with results that get contradicted or fail to replicate a few years later.
On my peak fitness enthusiasm I kept a rigorous food diary for some time and it was such a pain in the ass that I don't believe for a second that food diaries coming from people who are not 100% committed and interested in keeping one are accurate at all. People would often forget to log small snacks they have, or estimate portion sizes completely wrong, or neglect logging sauces, oils, condiments, etc.
What you describe is still an observational study, just a very expensive one now. It's still quite possible you'd fail to measure something important you hadn't thought of.
Better to spend some of that budget instead on a randomised controlled trial but there are likely issues with getting people to follow their prescribed diets to the letter
Really? I would think weight loss, inflammation, and psychological health measures would at least be affected on a timescale of a couple years, if not risks for things like cancer and heart disease.
Not for an observational study. There is simy too much variation and too many confounding factors. There would be no statistical power and infinite questions on the results.
Essentially everyone's condition and situation would be different.
Keep in mind that 1000 people is the size you might expect for a controlled trial where you change one single thing you expect to have a big impact like a cancer medication and even then you try to screen the patients to have as little variation as possible.
What would prevent us from doing a study like this: take 1000 diverse subjects, assign each of them a lab assistant, and for 2+ years, diligently track everything they eat, their exercise, sleep, etc. You could pay each participant and staff $100k/each, and the cost would be on the order of $400MM.
May not be epistemologically perfect given that people change their behavior when observed, but still superior to plenty of the stuff getting published now, and likely the knowledge gained for humankind would be worth many billions.