Lillian Wilson

The Obesity Code: Unlocking the Secrets of Weight Loss by Dr. Jason Fung

Obesity is a new epidemic of the 21st century. Find out how to prevent and reverse obesity with Fung's book 'The Obesity Code'.

‘The Obesity Code Unlocking the Secrets of Weight Loss’ by Dr. Jason Fung; A Book Review

The book has gotten 4.38 ⭐️ on GoodReads.

In the past four decades, the world has witnessed a concerning rise in obesity rates, transforming it into a pressing global epidemic. With each passing year, the numbers have soared, with drastic increases observed since the 1960s.

According to recent data from WHO, the number of obese individuals is close to 1 billion, with 39 million being children.

As the world confronts the magnitude of this crisis, understanding the causes, implications, and potential solutions of obesity becomes paramount. In this article, we delve into the book ‘The Obesity Code‘ by Dr. Jason Fung – an insightful read that sheds the light on far-reaching consequences of obesity and explores the pathways toward a healthier future.

Author’s background

Jason Fung is a medical doctor, nephrologist, and author who has gained popularity for his work on intermittent fasting and low-carbohydrate diets. He is the author of several books, including The Obesity Code and The Complete Guide to Fasting.

Fung is known for his approach to treating obesity and type 2 diabetes by addressing the root causes of these conditions rather than just treating their symptoms. He has also been a vocal critic of the conventional medical approach to treating type 2 diabetes, which he argues is ineffective and harmful to patients.

What is the book about?

The Obesity Code‘ by Dr. Jason Fung is a book that challenges the current nutritional dogma and provides a new framework for understanding and treating obesity.

The book is divided into six parts, covering topics such as the caloric theory of obesity, the hormonal theory of obesity, the social phenomenon of obesity, the role of macronutrients in weight gain, and guidelines for the lasting treatment of obesity.

Dr. Fung argues that the current understanding of obesity is flawed and that the hormonal theory of obesity, which focuses on the role of insulin in regulating body weight, provides a more robust explanation of obesity as a medical problem.

The book also discusses the role of genetics and environment in obesity, the association of obesity with poverty, and the importance of stress management and sleep improvement in controlling insulin levels.

Table of contents

  • Foreword
  • Introduction
  • Part 1: The Epidemic
  • Chapter 1: How Obesity Became an Epidemic
  • Chapter 2: Inheriting Obesity
  • Part 2: The Calorie Deception
  • Chapter 3: The Calorie-Reduction Error
  • Chapter 4: The Exercise Myth
  • Chapter 5: The Overfeeding Paradox
  • Part 3: A New Model of Obesity
  • Chapter 6: A New Hope
  • Chapter 7: Insulin
  • Chapter 8: Cortisol
  • Chapter 9: The Atkins Onslaught
  • Chapter 10: Insulin Resistance: The Major Player
  • Part 4: The Social Phenomenon of Obesity
  • Chapter 11: Big Food, More Food and the New Science of Diabesity
  • Chapter 12: Poverty and Obesity
  • Chapter 13: Childhood Obesity
  • Part 5: What’s Wrong with Our Diet?
  • Chapter 14: The Deadly Effects of Fructose
  • Chapter 15: The Diet Soda Delusion
  • Chapter 16: Carbohydrates and Protective Fiber
  • Chapter 17: Protein
  • Chapter 18: Fat Phobia
  • Part 6: The Solution
  • Chapter 19: What to Eat
  • Chapter 20: When to Eat
  • Appendix A: Sample Meal Plans (with Fasting Protocols)
  • Appendix B: Fasting: A Practical Guide
  • Appendix C: Meditation and Sleep Hygiene to Reduce Cortisol
  • Endnotes
  • Index

Key takeaways from the book

1Exercising is great for overall health, but diet plays a more significant role in weight management

‘Diet does 95 per cent of the work and deserves all the attention; so, logically, it would be sensible to focus on diet. Exercise is still healthy and important – just not equally important. It has many benefits, but weight loss is not among them.’

According to the book The Obesity Code, exercise is not as effective as diet in reversing obesity. The book argues that exercise is important for overall health and should be done regularly, but weight loss is not one of its main benefits. The book suggests that focusing solely on exercise to combat obesity is a flawed approach and that more attention should be given to addressing the root causes of obesity, such as diet and lifestyle factors.

2Fasting – an ancient remedy for reversing obesity

Fasting is considered an ancient remedy for reversing obesity. The book explains that fasting has been part of the practice of virtually every culture and religion on earth and that physicians have advocated fasting as far back as the mid-1800s. The book also cites several studies that confirm the effectiveness of intermittent fasting combined with caloric restriction for weight loss and improving important risk factors, including insulin levels and insulin resistance.

3To effectively control obesity, it is crucial to manage your stress levels

The Obesity Code explains that stress can cause weight gain and obesity through the release of cortisol, a hormone that stimulates insulin and insulin resistance. Chronic cortisol stimulation increases both insulin secretion and obesity. Therefore, the hormonal theory of obesity takes shape: chronically high cortisol raises insulin levels, which in turn leads to obesity.

The book suggests that reducing stress is difficult but vitally important, and recommends time-tested methods of stress relief, including mindfulness meditation, yoga, massage therapy, and exercise.

Strengths and weaknesses, according to readers’ reviews


  • Presents an evidence-based biological model of obesity that makes complete sense in its logical simplicity.

  • Includes just enough science to convince the sceptical scientist, but not so much that it confuses those without a background in biology.


  • The Obesity Code fails to address eating disorders and the potential risks of meal skipping. This overlooks the dangers for individuals with unhealthy eating habits and elevated insulin levels, who may develop binge eating disorders as a result.

Best quotes from ‘The Obesity Code‘

"Once we understand that obesity is a hormonal imbalance, we can begin to treat it. If we believe that excess calories cause obesity, then the treatment is to reduce calories. But this method has been a complete failure. However, if too much insulin causes obesity, then it becomes clear we need to lower insulin levels."
"Coffee, even the decaffeinated version, appears to protect against type 2 diabetes. In a 2009 review, each additional daily cup of coffee lowered the risk of diabetes by 7 per cent, even up to six cups per day."
"In 1960, we ate three meals a day. There wasn’t much obesity. In 2014, we eat six meals a day. There is an obesity epidemic. So, do you really think we should eat six meals day?"

Final takeaway

‘The Obesity Code‘ by Dr. Jason Fung provides a valuable and concise exploration of how bodies work in relation to obesity. With a significant amount of footnotes throughout the book, it offers a thorough examination of the subject. Whether you’re concerned about the rising global epidemic of obesity or simply interested in understanding how our bodies function, this book is definitely worth reading.

Where to buy

You may purchase ‘The Obesity Code‘ on Amazon at the best price. It is available in Kindle, paperback, and audio versions, so you are free to choose the format that suits you best.

Healthypedia FAQ

According to the WHO report, there are 1 billion people experiencing obesity, with 650 million adults, 340 million adolescents and 39 million children.

Obesity is a multifactorial condition, meaning that there are many factors that can contribute to its development. Some of the most common causes of obesity include genetics, environmental factors such as a sedentary lifestyle and unhealthy eating habits, hormonal imbalances, certain medications, and underlying medical conditions. Additionally, there is evidence that exposure to certain chemicals in the environment, known as obesogens, may also contribute to the development of obesity.

Insulin is the major hormone that drives weight gain, so the rational therapy is to lower insulin levels. There are multiple ways to achieve this, and we should take advantage of each one. The step-by-step approach to accomplish this goal includes reducing consumption of added sugars, maximizing protective factors such as fibre and vinegar, choosing only natural, unprocessed foods, balancing insulin-dominant periods with insulin-deficient periods, and addressing factors that affect insulin and weight loss such as sleep deprivation and stress. It is important to tailor the approach individually to address the cause of the high insulin levels.

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