The Hunger Code: Resetting Your Body's Fat Thermostat in the Age of Ultra-Processed Food

by Jason Fung

THE SEQUEL TO THE MULTI-MILLION COPY BESTSELLER THE OBESITY CODE

"Jason Fung nails it again in The Hunger Code. This book clearly and compellingly explains why most Americans are overweight and gives us a concise, evidence-based way to manage our weight with as little hunger as possible."—Dan Buettner, New York Times bestselling author of The Blue Zones

The Obesity Code helped thousands of people lose weight naturally.

The Hunger Code will help thousands more lose weight—and keep it off—in an era of weight‑loss drugs and ultra-processed foods…without counting calories.

For generations, we've accepted the story that weight loss can never last—that as soon as we go off the diet or stop taking the medication, we revert to our old habits, regain the weight, and the calorie-counting journey starts all over again. Traditional medicine continues to treat the symptom of weight gain rather than addressing its root causes. Too often, healthcare systems intervene with quick fixes and short-term solutions, ignoring the factors that lead to sustainable weight loss that can last a lifetime.

What if the secret to long-term weight maintenance and better health isn’t just about what you eat—or even when you eat—but why you eat?

With the food industry's reliance on ultra-processed foods and the popularity of Ozempic and Mounjaro, understanding the forces behind why we eat is more important than ever before.

In The Hunger Code, New York Times bestselling author Dr. Jason Fung reveals the three powerful forces that drive us to
Physical HungerEmotional HungerSocial Hunger
Dr. Fung also introduces the concept of the body’s “fat thermostat”—a biological “set point” that regulates how much fat your body tries to maintain. Guided by hormones and metabolism, this internal system drives hunger and energy use, explaining why lasting weight loss requires more than just willpower …

With three Golden Rules and 50 actionable tips, The Hunger Code empowers you to recognize and respond to hunger appropriately. Learn how to slow digestion, break emotional eating cycles, and overcome social pressures to eat constantly, so you can maintain a healthy weight—from scratch, after fasting, or after using weight‑loss drugs.

Genres: Nonfiction, Health

279 pages, Kindle Edition

First published March 3, 2026

Reviews

[Donna · Rating 4 out of 5]

I've read this author before and I have also heard him as a guest on several podcasts promoting this new book of his. I like his logic and his overall message and I'd read anything that he puts out there.

In this one, he dives into hunger....what it is, how to keep it at bay, and what to eat to prevent frequent trips to the vending machines. He also expands on ideas he's introduced in his previous books such as the role of insulin in fat storage, fasting, diabetes, obesity, etc. He challenges much of what we've all been taught about nutrition since the 1980's. I love that.

What stood out the most is how much more he explores weight loss and how hunger can be controlled. This all seemed more detailed and more applicable for daily use. I loved that focus.

Now with all that said, I can see this book receiving some criticism. Given Fung's reputation for challenging the standard of care, he naturally has his share of hecklers. At times, I found myself wondering whether his intended audience was the people he wants to help or the critics he's trying to persuade. His humor and occasional language choices didn't always strengthen his message and may turn some readers off.

However, I still found this one worthwhile and I'd recommend this to anyone who is struggling with diabetes and the complications that go along with that. I hope this sparks more meaningful conversations about preventing disease and reversing it rather than simply managing it. So 4 stars.

[༺ Jason ༻ · Rating 4 out of 5]

This is a companion to his exceptional book The Obesity Code. That book was a game changer and highly recommended. This book he goes into more detail about what things that help control our hunger. His logic has been sound and a simple solution well just works. Although I did enjoy it and recommend you read both, but if you’re just going to read one that you want a complete picture go with The Obesity Code. For that book alone I can’t thank Dr. Fung enough. This book was an excellent follow up.

[Aaron Beyk · Rating 5 out of 5]

Seek the cause(s), find the solution

A more complete version of the obesity code that factors in more of the effects causing the hormonal imbalances driving obesity. Factors in the importance of UPFs in the diet and how the environment we live in today is obesogenic, not in an environmental pollutant manner, but in a sociological and economic manner. I hear lots of allusions to the “trapped fat” hypothesis— what came first, the chicken or the egg—is it the behavior of overeating calories or the hyperinsulinemia? I also hear lots of points made by other authors like Lustig and Moss— this is important as the ideas of IPF’s and leptin resistance are not only coming from Fung, validating his points. Insulin’s action to cause the preferential storage of nutrients away from the blood and into cells, causing overeating is arguably the main physiological cause of the obesity epidemic, but Fung compiles the environmental and emotional factors that would cause insulin-ogenic feeding to begin with. By recognizing the multifactorial causes of the neuroendocrine imbalances seen in obesity, Fung presents practical ways to modify the real causes of the physiological changes seen in obesity. I do believe that by recognizing our lever to pull in this conversation as insulin effects from the diet, we can make great strides in our overall health (ie, having more nutrients available in the blood to be able to do hobbies that allow us to cope well with the stressors that would cause hedonic eating). I don’t know which lever is best to pull here, but maybe by attacking the issue from many sides (a method that could be detracted from this read— perhaps obesity is caused in a particular person because of their life stressors causing hedonic hunger and homeostatic hunger from the UPFs causing insulin resistance in the VMH, blocking leptin signaling), we can attack the multifactorial cause of the most prominent epidemic in human history.

[Leah Shelton · Rating 5 out of 5]

The Hunger Code is an excellent, approachable, and more nuanced sequel to The Obesity Code. Although there is no “one size fits all” approach to nutrition, Fungs “golden rules” are broad enough to be applied to any individual. As a physician, I particularly appreciate how Fung explains complex scientific topics in multiple ways, first using medical jargon, then using lay-person terms, and then often using metaphors to solidify understanding.

I would highly recommend this book to anyone who wants to learn more about nutrition and obesity for themselves, their patients, or their community.

[Suzanne · Rating 3 out of 5]

I am a regular reader of Jason Fung’s books and have learned a lot from them. THE HUNGER CODE is far less focused than his previous work and suffers from a desire to be all things to all people. I had hoped to learn more about GLP-1s but the addition of them to the book was minor; they were not well addressed. Much of this book can be found in previous work. New readers will benefit from the information, as I have. There were also sections devoted to behavioral mod techniques to manage eating. Again, this will be most helpful to new readers of his work. I received my copy from the publisher through edelweiss.

[Paul Moore · Rating 5 out of 5]

Straight forward, clear, practical,and meaningful guidance for weight control

This book is an easy read. It is well organized, logical and convincing. It is a wonderful manual for healthly eating through life.

[Jason Buckley · Rating 4 out of 5]

Great book and very informative. Lots of reference to his previous book The Obesity Code but the books stands on its own.