This is definitely part of it, but I feel like it underplays the fundamental difficulty of studying nutrition. Put yourself in the shoes of someone who wants t

This is definitely part of it, but I feel like it underplays the fundamental difficulty of studying nutrition. Put yourself in the shoes of someone who wants to study this, and you rapidly see the problems. Effects of nutrition take many years to show, so you're generally going to need to track people for years. People move, get bored of talking to you, die, etc. Their diet also varies greatly over time. They don't always remember what they ate, and certainly can't quantify it with any degree of accuracy. If you perform some intervention, it's hard to know that the people actually complied with it. You can do it in the short term by having an in-patient setting, but again you miss the long term effects, which are really what matters to most people. I feel like people reach too easily for conspiracy theories these days…