Thanks for asking a serious question. Getting a PhD in nutrition is the same as another other PhD -- you study at a graduate program under an existing tenured

Thanks for asking a serious question. Getting a PhD in nutrition is the same as another other PhD -- you study at a graduate program under an existing tenured professor in that field, do original research and successfully defend your dissertation. My wife happens to have gotten her undergrad degree at a great school, did her dietetic internship at an excellent hospital and worked as a dietitian for a decade before returning to do her graduate work at an even better school. But one can call themselves a "nutritionist" with no training whatsoever; the term isn't legally protected like "doctor" is. Nutrition is a field where the underlying science is difficult as, say, cryptography, but is far more obviously relevant to the average person's life. So popular books are easy to get published and there's no guarantee that the author has much actual nutrition training at all. And again unlike crypto there are several large, entrenched, deep-pocketed interests in America that aggressively promote low-quality science to increase consumption of their products. When you make tens of billions of dollars per year, it's not too hard to fund a hundred studies that year and use p-hacking and other tricks to get at least a couple to come out with some result that shows your industry in a good light. Then you make sure that those get covered with a headline in some newspaper or magazine. > Are there experts with a track record of scientific rigor? I'm not the one with the PhD but I know that my wife is a big fan of both Walter Willett and Marion Nestle.