The Obesity Code

Unlocking the Secrets of Weight Loss

by Dr. Jason Fung

4.6(36,826 ratings)

13 min read

Brief overview

This book explains why controlling insulin levels is key to addressing obesity. It challenges the idea that eating fewer calories is all that matters, instead showing how sugar, refined carbs, and meal timing affect the body’s hormones. By offering practical methods such as intermittent fasting, it empowers readers to break the cycle of weight gain and achieve real, lasting change.

Introduction

Obesity rates have soared over the past few decades, and many traditional weight-loss strategies have failed to reverse this trend. For years, we’ve been told to cut calories and exercise more, yet people still struggle to maintain a healthy weight.

This book starts by questioning whether the standard approach—Eat Less, Move More—actually addresses the root cause. It suggests that there must be deeper mechanisms behind persistent weight gain.

By examining historical eating patterns and modern diets, this overview sets the stage for a fresh perspective on weight management. It points to the notion that hormones, especially insulin, play a central role.

As you move through the chapters, you’ll discover how certain foods and habits raise insulin levels, triggering the body to store fat. Understanding this process is the critical first step to success.

Identifying the true cause of weight gain allows you to target the problem rather than the symptom.

A New View of Weight Gain

Traditional wisdom often blames excess body fat on lack of willpower or laziness. Yet real-world evidence and scientific data reveal that the primary issue is not a person’s character but biological responses to modern foods.

Family history does play a role, but genetics alone can’t explain why obesity surged quite suddenly in recent decades. Instead, cultural shifts in how we eat—more snacks, sugary drinks, and processed meals—have strongly influenced our health.

Lifestyle changes, like driving everywhere instead of walking, might seem to blame. However, research often fails to connect small variations in exercise with the dramatic rise in obesity rates.

This book highlights a more unified explanation: hormones are the regulatory forces. While many factors influence health, the evidence suggests that persistent weight gain is closely tied to insulin and insulin resistance.

“We do not get fat because we overeat; we overeat because we’re getting fat.”

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What is The Obesity Code about?

The Obesity Code: Unlocking the Secrets of Weight Loss delves into the hormone-driven causes behind obesity, focusing on insulin and its powerful effects on weight regulation. Instead of emphasizing strict calorie control or extreme dieting, Dr. Jason Fung shows how understanding insulin resistance can help readers achieve sustainable weight management. By presenting practical steps like intermittent fasting and limiting refined carbohydrates, this book highlights how small shifts in eating habits can support stronger metabolic health.

In a clear, research-based lens, the author challenges common diet myths and reveals why traditional approaches often fail. Readers will discover how stress, meal timing, and the modern food environment can undermine attempts at losing weight. Equally important, the book spotlights ways to break these cycles, blend healthy eating with daily routines, and create long-term success.

Review of The Obesity Code

This book’s greatest strength lies in its evidence-based approach to understanding obesity as a chronic disease. Dr. Fung treats insulin as a central player, giving readers a new perspective on how blood sugar levels, meal timing, and refined sugars work together to affect weight gain. The book excels at offering actionable strategies, such as intermittent fasting, that fit seamlessly into busy schedules. Complex medical concepts are distilled into everyday language, making the information accessible to a broad audience.

Readers who enjoy candid, data-backed insights will appreciate the clarity of Dr. Fung’s writing and the logical flow of each chapter. The relevance spans across professions, from healthcare providers to busy parents looking for straightforward nutritional guidance. The final verdict: this is a must-read for anyone tired of short-lived diets and ready for a fresh, science-anchored solution to weight loss.

Who should read The Obesity Code?

Healthcare professionals looking for fresh, science-based perspectives on weight management
Busy individuals who want realistic meal strategies and intermittent fasting tips
People experiencing ongoing weight struggles and seeking a sustainable plan
Nutrition and fitness enthusiasts aiming to deepen their knowledge of metabolic health

About the author

Dr. Jason Fung is a Toronto-based nephrologist and a world-leading expert in intermittent fasting and low-carb diets. He completed his medical training at the University of Toronto and a fellowship in nephrology at UCLA. With over 2 million copies sold worldwide of his book "The Obesity Code: Unlocking the Secrets of Weight Loss," Dr. Fung has challenged conventional thinking about obesity and introduced dietary strategies to manage it. He is also the author of other influential books, including "The Diabetes Code" and "The Cancer Code," and is the co-founder of The Fasting Method.