I recently read and enjoyed “The Longevity Solution,” a book Dr. Fung co-wrote with Dr. James DiNicolantonio. It expanded my understanding of the tension between growth and longevity, and dug into some theories of health that went beyond insulin, obesity, and fasting – for example, there was a lot in it about protein’s impact on the body – animal vs. plant proteins, ideal amounts of protein to eat at different times in life, and the role of mTOR activation in aging. Very interesting ideas here if you want to go beyond what is offered in “The Obesity Code.”
There was also a section in the book dedicated to salt and magnesium, which I imagine can be largely credited to Dr. DiNicolantonio, who wrote “The Salt Fix”. I decided to give Dr. DiNicolantonio’s book a try, and while there was a lot I appreciated about it, I felt like he made a few confusing claims about the relationship between salt and insulin in the body. In “The Obesity Code” and “The Diabetes Code”, I think Fung did a good job of building very clear theory diagrams and explaining the big picture of all the mechanisms at play. As far as I can remember, Fung doesn’t mention low sodium intake as playing a significant role in the rise of insulin sensitivity. In DiNicolantonio’s book, he claims that “ Insulin resistance and higher insulin levels are likely physiological adaptations to salt restrictions” (98) and that “Restricting your salt intake can…constrict your blood vessels and decrease your muscles’ ability to absorb glucose, which may lead to chronic high insulin and – you guessed it – fat storage” (95). DiNicolantonio does go on to point out sugar’s role in all of this…but doesn’t really go back and fully explain how sugar’s role compares to salt’s.
I guess I’m just wondering what other people make of these claims about the role salt plays in insulin resistance, and if Fung himself has clearly indicated anywhere that salt restriction could play a role in the development of obesity or diabetes. I feel like DiNicolantonio did convince me that salt shouldn’t be demonized as much as it is, but he didn’t convince me that low salt intake could lead to insulin resistance or obesity.
OP, I’m with you on this.
I’ve long been of the view that salt is often vilified far beyond what is justified and some people who completely avoid or heavily restrict their intake might well be worse for the wear for doing so. I credit Mark Sisson for this view; he covered this on his blog many years ago.
But at the same time, some people really do need to carefully limit their intake, and I also don’t quite buy into the apparently emerging belief that salt is a miracle worker or has some kind of magical properties (figuratively or literally). And I don’t think there’s any particular benefit to using the fancy, expensive Dead Sea or Himalayan salt, beyond perhaps a slightly different flavor, or any particular harm in using plain old iodized table salt beyond what would be expected with overconsumption of any salt.
All that to say, I think you’re right to be unconvinced. It sounds like DiNicolantonio’s ideas about a link between salt and insulin resistance, T2D and obesity, are not well supported.