Nutrition is a key part of overall health. A lot of issues discussed on the Health page can be handled or at least helped by nutrition. What you eat, how you eat, and when you eat is key for achieving a healthy metabolism (regulation of glucose, insulin, fat, and more). After the table of contents, you’ll see an important note on epidemiology and the problems with nutrition science before diving into what we actually do agree on, and then each of the core nutrition sections.
A lot is written about nutrition, often pointing to studies that are either extremely poorly designed or based on epidemiological evidence. Nutritional epidemiology looks at data and creates correlations between populations and health outcomes in order to try to discover links between certain foods and certain ailments.
Epidemiology can work for certain cases, for example the link between smoking and lung cancer looked at 7M people and found it 7x more likely that smokers develop lung cancer compared to non-smokers. This is pretty convincing! In other cases, the epidemiological evidence is strengthened by having genetic similarities between populations—in twin studies for example, or looking at different populations from different locations in the world.
<aside> ⚠️ IMPORTANT! READ THE TEXT BELOW!
BUT in nutrition, most epidemiological studies—and these are the ones that are quoted in articles in The New York Times, Forbes, TIME, and more—take a correlation and extrapolate it to explain the reason for the health outcome. Correlation is not causation. Just because there is a link between two variables, it does not mean that one caused the other. This is super super super important and is completely thrown out the window in much of what you read about nutrition in popular culture, the news, and social media.
Also, much of the data in these studies comes from self-reported data, which is notoriously unreliable. Generally, this kind of data for nutrition should not be used at all.
The information I try to use to inform what’s written here is based on studies—as much clinical trial data (randomized controlled trials) as possible, and mechanistic explanations from experts in their fields. This information does not and should not come from journalism, as it’s mostly hot garbage when it comes to nutrition.
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The rest of this page dives fairly deep on a number of topics, including diets and models of obesity and disease. Before we get to that, here are some obvious things that the entire (educated) nutrition community agrees on, and some common nutrition myths.
There are a handful of things that any proper nutrition scientists agree are objectively healthy: