---
title: "Dr. Jason Fung, MD: Researcher Cited by RealFoods"
url: https://realfoods.app/authors/jason-fung
description: "Dr. Jason Fung, nephrologist and author of The Obesity Code, writes on insulin and fasting. RealFoods cites his work but is not affiliated with him."
---

Researcher we cite

# Dr. Jason Fung, MD

Nephrologist, Intermittent Fasting Expert

> Jason Fung is not affiliated with RealFoods and has not reviewed or endorsed the app or the Weight Impact Score.
>
> RealFoods cites Jason Fung’s published work as one of its sources. RealFoods articles are written by [Dino Pohilj](https://realfoods.app/authors/dino-pohilj).

Dr. Jason Fung is a Canadian nephrologist and author who has written widely on therapeutic fasting and type 2 diabetes. His framework treats chronically elevated insulin as a primary driver of obesity.

Fung came to insulin through kidney medicine, not weight loss. Working as a nephrologist with patients who had diabetes and obesity, he kept seeing insulin, not calorie intake, as the variable that predicted who got sicker and who improved. The Obesity Code turned that clinical observation into a full framework: obesity is a hormonal disorder driven by chronically elevated insulin, and, in his view, any approach that does not lower insulin is treating the wrong target.

Fasting is the lever Fung uses most, because it is the most direct way to give insulin an extended break. In The Complete Guide to Fasting, he lays out how eating windows of varying length can let insulin fall low enough for the body to use stored fat for fuel. Fasting is an option some people choose, not a requirement. His writing on therapeutic fasting is one of the sources RealFoods draws on for its fasting content. Fung has not reviewed or endorsed any RealFoods feature.

The Diabetes Code extends the argument to type 2 diabetes specifically, making the case that addressing insulin resistance matters more than chasing blood sugar numbers alone. That distinction, blood sugar readings versus the insulin resistance behind them, is one of the book's central themes. Anyone new to fasting can see how the stages work in practice below.

Fung's nephrology background also shapes how he talks about obesity and metabolic health more broadly. Kidneys are deeply involved in blood sugar and insulin regulation, and Fung has argued that treating obesity as simple math, what goes in against what goes out, ignores the hormonal signaling his own field of medicine takes for granted. That is part of why his fasting protocols are framed clinically, as a tool for lowering insulin on a schedule, rather than as a lifestyle trend. His wider point is that obesity and metabolic health sit downstream of a hormone, not a habit of overeating.

## Key works

- The Obesity Code (2016)
  Fung's clinical case that insulin, not calories alone, is the hormonal driver of body weight regulation.
- The Complete Guide to Fasting (2016)
  A practical and clinical guide to intermittent and extended fasting for metabolic reset.
- The Diabetes Code (2018)
  Fung's case for targeting insulin resistance in type 2 diabetes, not blood sugar readings alone.

## Areas of expertise

- Intermittent Fasting
- Insulin Resistance
- Type 2 Diabetes
- Therapeutic Fasting
- Obesity
- Metabolic Health
- Nephrology

## Official profiles

- [drjasonfung.com](https://drjasonfung.com/)
- [www.wikidata.org/wiki/Q61677978](https://www.wikidata.org/wiki/Q61677978)

## Continue exploring the science

- [The Stages of Fasting](https://realfoods.app/fasting-stages)
- [What is Insulin Resistance?](https://realfoods.app/what-is-insulin-resistance)
- [Signs Your Body May Be Burning Fat](https://realfoods.app/how-to-know-if-your-body-is-burning-fat)
- [How to Lower Insulin Naturally](https://realfoods.app/lower-insulin-naturally)