I have consciously decided to let the arguments for high protein diets pass me by, despite how convincing some of the research and underlying mechanistic claims sound. Humans have been cycling through high -protien, -fat, and -carb diets since we developed enough of a surplus to choose, and I’m pretty sure if any of them were that superior to the others it wouldn’t have been supplanted. I would say “everything in moderation”, but that is just a zen way of saying “Eat the correct amount. Idiot.” which I don’t think is very helpful.
HAES brings up a more constructive suggestion: eat fiber. Fiber* is usually left out of the macronutrient triumvirate, but so is water, and water is extremely useful. Off the top of my head: Fiber has the advantage of being natural**, because our ancestral foods had much more fiber than our current ones, yet its lack of calories is well suited to our current, couch-based, lifestyle. It evens out digestion of other nutrients, reducing the destructive sugar/insulin boom and bust cycle. It simultaneously treats diarrhea and constipation (if you drink enough water, which you should anyway). Have you ever wished you could eat a good thing and have it cancel out a bad thing?
Well, that might actually be true if the good thing is fiber, and the bad thing is not cocaine.
Here is where I meant to track down all the good things HAES says about fiber, but when I read it more carefully. I realized most of what it was praising was fruit, with the implication that fiber was the reason fruit is beneficial. The one actual fiber claim is that high-glyemic diets increase the risk of type 2 diabetes unless the diet is also high in fiber (five sources, all of which say nice things about fiber, one of which is actually about type 2 diabetes. The paper did conclude that fiber fights type 2 diabetes, but it was a post-hoc survey, which is a weak methodology). However, those other four sources also say pretty good things about fiber, just not the one the book claims they did. I think we are all on board with “fruit and whole grains” > “potato chips and soda”, although I’m severely disappointed that this of all books is backing that up with data on weight loss, rather than actual health outcomes.
But Dr. Wikipedia has many very specific nice things to say about fiber, and it cites much more relevant sources. Fiber increases micronutrient absorption (a little). Fiber increases nutrient absorption (more). Fiber fights inflammation. Basically, it does everything good and nothing bad. So while HAES didn’t lay out its case properly, fiber is definitely good, and I look forward to finding out who takes this too far and what the negative effects are.
*Definition of fiber varies a little from institution to institution, so for clarity: I am defining fiber as carbohydrates that are not broken down for energy in the human body. It’s worth noting that there are two contributors to whether an organism can digest food: its own enzymes, and the bacteria in its digestive track. Termites can’t naturally digest wood, but they house a bacteria that can.
**It’s easy to oversell “naturalness”, but when you have a mission critical system made of complex legacy code no one understands, sticking close to its original environment is a good default strategy.