Last year I started getting really interested in nutritional and metabolic health (doing a pretty deep dive starting with lots of medical talks, and subsequently reviewing tons of the primary research (all about that PubMed and Sci-Hub life)). Honestly, I’ve been working on a variation of this post for almost a year, but as my collected research kept growing, I continued to put this off. This is long overdue, so I’ll just start off publishing some stuff and go from there (eventually, I will be shifting most of this to a platform that allows me to better update/revise things). A few of the things I’ve learned:
- The obesity epidemic is insane. In 1996, no state in the US had an obesity rate of >20%. By 2007, no state had an obesity rate of <20% (PDF). As of 2016, the US obesity rate is 39.8%. According to the 2017 CDC reports, 9.4% of the US population has diabetes, and 33.9% of adults are prediabetic. This is also not limited to the US. It’s estimated that 9.1% of adults suffer from T2D. In China, diabetes was <1% in 1980, but in 2013 was 10.9%. In a just published study, only 12.2% of Americans were categorized as metabolically healthy. The Milken Institute also just published an estimate that the direct and indirect costs of obesity were at $1.7T, or 9.3% of the US GDP (see also WOF estimate, meta-analysis)
- These numbers have continued to skyrocket despite Americans doing what they’ve been told: exercising more, drastically cutting down on animal fat and replacing with PUFA consumption (see also), lowering LDL and saturated fat consumption, and reducing red meat and dairy consumption (Things that have changed: eating way more often, eating way more sugar, oil, and processed foods, also more wheat)
- Non-Alcoholic Fatty Liver Disease (NAFLD) is a related condition which is also now epidemic. According to the NIH, “Between 30 and 40 percent of adults in the United States have NAFLD.”
- Your doctor is likely clueless about these life-style driven chronic/metabolic diseases. On average, U.S. medical schools offer only 19.6 hours of nutrition education across four years of medical school, according to a 2010 report in Academic Medicine. Of course, any nutrition education would have likely been driven by the US dietary guidelines, which have been wrong from their start (1980).
- The calories model of weight gain seems pretty misguided, as every aspect of metabolism in the human body is highly regulated (hunger, satiety, fat-burning, metabolic rate) by hormones. The standard recommendation to eat less and move more doesn’t work (here’s just one of many studies on how/why)
- Nutritional science is terribad. Poor methodology, poorly controlled studies, manifold confounders, poor reproducibility, lots of statistical funny business from p-hacking to abuse of relative risk, huge bias and conflict of interest, and lots of policy/institutional bias locked in from very poor evidence decades ago. Some outright corruption, as well, of course. Nutritional journalism on average is even worse.
- Basically, anything is better than the Western Diet (aka SAD: Standard American Diet) but in general, a healthy diet is probably one made up of foods that we’ve adapted to eating over millions of years (but also, probably more specifically, what your recent (500-1000yr) ancestors ate). While studies of traditional diets of healthy populations don’t point to a single optimal diet, there are some commonalities: whole unprocessed foods (which by default excludes sugar, refined carbs, industrially processed seed oils – the biggest offenders IMO), and tighter eating windows (<10-12h).
- With this in mind there are a lot of dietary interventions that are very effective to get healthier relatively quickly (besides improving insulin sensitivity, reversing NAFL, these interventions also reduce inflammation, and increase autophagy/cellular repair mechanisms), but more important I think is to having a framework where you can both evaluate claims but also test personal efficacy via a set of surrogate and subjective markers.
I’ll save the detailed look at my personal results for another post, but I’ll summarize a bit of my path. Early on, I ended up stumbling on an interview with Jason Fung, which seemed to make a lot of sense. Now, not being a complete nutritional nitwit (just a pretty average one), I had seen some of Robert Lustig’s talks and Gary Taube’s writing previously on how terrible sugar was for you, but despite cutting out sugary sodas, or doing bouts of paleo-ish meal plans, it never really stuck. However, as I dug more, I ended up finding that despite my original claim of not being a nutritional nitwit, that I actually was – most of the nutritional common wisdom I thought I knew was being contradicted. I’ve curated a list of some of the most interesting YouTube talks/presentations I’ve come across. These are all well sourced, and starts first w/ some more general overviews of the hormonal mechanisms of metabolism etc, and then moves into deeper topics from there:
If you’re like me, you’re probably (rightly) skeptical of using YT talks/presentations as primary sources, especially in a field like nutritional science, where snake oil and bad science is the norm. So I started spelunking through the sources, and after collecting a few dozen, realize that I need a better research manager and downloaded Zotero for the first time in about a decade (it’s better than it was back then, a little worse recently as many of the integrations/plugins are now broken). I also started writing my own custom exporter, but luckily, I found a nice one called zotsite that works great, and I’ve written a cronjob for it now.
I’ve embedded an export of the nutrition sources I’ve collected below, but you can also access it directly at https://randomfoo.net/nutrition/ – it’s about 3500 sources at the moment (abstracts/articles/studies/reviews etc). I’m still adding onto this (turns out, tracking down/reading nutrition/medical research has been a bit of a full time hobby this past year), but I hope to make a second pass where I do a better job organizing these soon, adding notes, and getting any missing full PDFs through sci-hub or academic institution access. For the less ambitious/more sane, I have also curated a few reviews/overviews that I feel are the most compelling/interesting things I’ve stumbled across: https://randomfoo.net/nutrition-bestof/
As an aside: early on I stumbled on SCI-FIT which has also been collecting references, but mine is sourced almost entirely independently – again, when I get a chance, I’d like to sit down and cross-reference (I feel like being able to properly annotate/narrativize all these resources is a real weakness w/ Zotero, though).
As I mentioned, my plan is to try to publish some writeups into a better platform at some point, but in the meantime, I’ll probably be a little less precious and post some stuff on the blog as well.