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Jason Fung isn’t the first person to talk about intermittent fasting—but he’s become the go-to guru on the subject for many of those in Paleo/Keto/Low-Carb communities.
Jason Fung is a nephrologist—a kidney doctor—and the overwhelming majority of his patients were diabetics. (Type 2 diabetes is by far the biggest cause of kidney disease.) He treated his diabetic patients in all the conventional ways, often with drugs like insulin that had the potential to make things even worse by causing more weight gain.
“I’d give them insulin, I’d give them drugs,” he told me in an interview. “And in the end, the diabetics still got kidney disease. It wasn’t like anything was getting better.”
The solution was obvious. “If type 2 diabetes is causing kidney disease, then the solution is to get rid of the type 2 diabetes”.
And that meant controlling blood sugar and insulin.
If you don’t know (or don’t remember) the story of insulin, here’s a quick recap: Insulin is the hormone that rises precipitously in the presence of high blood sugar. Its job is to get that sugar out of the bloodstream and deposit into cells. But when you eat too much sugar, the system breaks down.
When blood sugar and insulin are constantly being driven to high levels—as they are with the standard American diet—insulin’s ability to regulate things starts to diminish. You develop a condition called insulin resistance, which we now know plays a role not only in diabetes and obesity, but in heart disease and Alzheimer’s.
(Did I mention that insulin’s nickname is “the fat storing hormone”?)
Ever since Robert Atkins, controlling insulin has been a raison d’etre for low-carb diets.
And that’s what led Jason Fung, MD—nephrologist—to investigate low-carb diets, particularly ketogenic diets, which count decreased insulin resistance as one of their primary benefits. He became an advocate for keto diets because of that strict limit on sugar, and he became an advocate for intermittent fasting because it was another way to limit the amount of time a the body spends in a high-insulin state.
No wonder he’s a friend to low-carb. Low-carb diets are all about staying out of high-insulin states.
And in case you forgot why that’s important, insulin resistance is strongly linked to a number of diseases besides diabetes and obesity, including:
- Heart disease
- Alzheimer’s disease
- High blood pressure
- NAFLD (nonalcoholic steatohepatitis—fatty liver disease)
- Polycystic ovary syndrome
- Gastroesophageal reflux disease (GERD)
- Obstructive sleep apnea.
“Like caloric restriction,” says author, blogger and low-carb icon Dr. Michael Eades, “intermittent fasting reduces oxidative stress, makes animals more resistant to acute stress in general, reduces blood pressure, reduces blood sugar, improves insulin sensitivity, reduces the incidence of cancer, diabetes, and heart disease.”
Dr. Eades points out that in animal studies, intermittently fasted animals greatly increase their levels of brain-derived neurotrophic factor (BDNF), a substance that not only increases the growth of new nerve cells in the brain but is also neuroprotective against stress and toxins.
There are a ton of ways to do intermittent fasting and it’s easy to find terrific info about it online, so we won’t go into the various ways to do it here. (Fung’s book with Jimmy Moore, The Complete Guide to Fasting, is a great guide to the current state-of-the-art).
The point is that intermittent fasting has a ton of benefits and has been incorporated into a lot of programs. Bulletproof recommends intermittent fasting. Many of the keto programs use it. “If you buy into the idea that the Paleolithic diet is the optimal diet for us today because it is the diet we were molded by the forces of natural selection to perform best on, then you should probably also buy into the idea that a meal timing schedule more like that of Paleolithic meals would provide benefit as well,” says Dr. Eades. “I would think that the optimal way to go would be to follow an intermittent fast using low-carb foods during the eating periods. One would get the best of all worlds health-wise this way” (1).