The reader's edition
The Hunger Code: Resetting Your Body's Fat Thermostat in the Age of Ultra-Processed Food: the summary
Jason Fung is a Toronto kidney specialist best known for The Obesity Code and his work on intermittent fasting. The Hunger Code is his follow-up, and it moves the question from what and when you eat to why you feel hungry in the first place. He argues that the body defends a fat set point, a thermostat run by hormones such as insulin, and that ultra-processed food and constant eating push the setting up. He sorts hunger into three kinds, homeostatic, hedonic and conditioned, and answers them with three golden rules: avoid ultra-processed food, build in a regular fasting period, and redesign your surroundings and social habits. Around those rules he sets dozens of short practical tips, and he draws on research into hunger hormones and on the new weight-loss drugs such as Ozempic. Read a chapter at a time, with a printable action book at the end.
- Jason Fung
- 2026
- 4 chapters
- 5 min read
- 9 takeaways
This is HourLife's reading of The Hunger Code: Resetting Your Body's Fat Thermostat in the Age of Ultra-Processed Food, in our own words. It is not a substitute for the book.
Chapter 01
Before you start
The book in a minute
Tap a paragraph to highlight it. Turn pages with the arrows, the arrow keys, or a swipe.
Jason Fung is a Toronto kidney specialist best known for The Obesity Code and his work on intermittent fasting. The Hunger Code is his follow-up, and it moves the question from what and when you eat to why you feel hungry in the first place. He argues that the body defends a fat set point, a thermostat run by hormones such as insulin, and that ultra-processed food and constant eating push the setting up. He sorts hunger into three kinds, homeostatic, hedonic and conditioned, and answers them with three golden rules: avoid ultra-processed food, build in a regular fasting period, and redesign your surroundings and social habits. Around those rules he sets dozens of short practical tips, and he draws on research into hunger hormones and on the new weight-loss drugs such as Ozempic.
Below are the 9 ideas HourLife readers vote up most, each in our words with a note on what it asks of you, and then the steps that put them to work.
Chapter 02
What readers keep
The takeaways
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1
HourLife takeaway
Hunger, not willpower, decides how much you eat, so a diet that leaves you hungry is built to fail.
Fung's starting point is that cutting food without dealing with hunger tends to make hunger louder, and most people regain what they lose. He frames this book as the sequel to The Obesity Code, with hunger itself as the thing to fix.
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2
HourLife takeaway
Your body defends a fat set point the way a thermostat defends the temperature of a room.
Eat less and the body can push back with more hunger and less energy spent. Fung's aim is to lower the setting rather than fight it every day. Most researchers agree the body defends its weight to some degree, but how fixed that set point is remains debated.
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3
HourLife takeaway
There are three hungers, homeostatic, hedonic and conditioned, and each one needs a different answer.
Homeostatic hunger is the body's need, run by hormones. Hedonic hunger is eating for pleasure or comfort. Conditioned hunger is set off by places, times and people. Treating all three as one problem is why a single rule rarely holds.
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4
HourLife takeaway
Two foods with the same calories can send opposite signals: one says store, the other says stop.
Fung contrasts cookies, which push insulin up and favour fat storage, with eggs, which raise fullness hormones such as GLP-1. In his view the hormone response matters more than the calorie count. That is his position; many nutrition researchers still treat calories as the main lever.
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5
HourLife takeaway
Ultra-processed food feeds more than one hunger at once, which is why it is so hard to stop eating.
It is less filling, built to taste good, cheap and everywhere. That is why avoiding it is the first of Fung's three golden rules. Researchers broadly agree these foods make overeating easier, even where they argue about why.
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6
HourLife takeaway
A daily stretch without food gives insulin time to fall and the body time to use what it has stored.
A regular fasting period is the second golden rule. It can be as plain as not eating after an evening hour, or not eating in front of the TV. Anyone taking medicine for diabetes or blood pressure should plan this with a clinician first, because doses may need to change.
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7
HourLife takeaway
Conditioned hunger is learned, so you can unlearn it by changing the cue.
The cinema, the office snack table, the game on TV: none of them make the body need food, yet they reliably start the urge. Fung's third golden rule is to redesign your surroundings and your social habits so the cue stops firing.
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8
HourLife takeaway
Stress and short sleep raise cortisol, and cortisol raises physical hunger.
Fung counts cortisol among the hormones behind homeostatic hunger. So some of the fixes for appetite are not about food at all: a late night or a hard week can show up as hunger the next day.
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9
HourLife takeaway
Drugs like Ozempic work by quieting hunger, which suggests hunger was the problem all along.
Fung's point is that weight tends to return when the drug stops, because the hunger signals come back. The book covers keeping weight steady after a fast or after coming off these drugs. Starting, stopping or tapering any medicine is a decision to make with your prescriber.
Chapter 03
Put it to work
Your action book
Do the setup steps once, then keep the habits going. The setup changes your week; the habits keep it changed after the first good one.
The download puts this whole reading and a printable action book in one PDF: the setup checklist, then a page of real calendar days for each habit, starting on the day you choose.
Set up once
Keep a three-day hunger log
Each time you want to eat outside a meal, note the time, where you are, and which hunger it feels like: body, pleasure or cue. The hunger check on this page keeps the tally for you.
Swap your three most-bought packaged foods
Look at your last grocery receipt and circle the three ultra-processed items you buy most often. Pick a whole-food stand-in for each and buy that instead this week.
Set a kitchen-closed time
Choose an evening hour after which you don't eat, and tell the people you live with. If you take insulin or other diabetes medicine, agree any fasting window with your clinician before you start.
Move the cues out of sight
Put snacks in an opaque tin on a high shelf, clear the desk drawer, and leave the counter bare. Food you can't see starts fewer conditioned urges.
Write down a default first meal
Pick one first meal built on protein and fibre, such as eggs with vegetables or beans on wholegrain toast. Write it on the fridge so the morning needs no decision.
Keep it up
Eat protein and vegetables first
At each meal, start with the protein and the vegetables. When you eat starchy or sweet carbohydrates, have them alongside fat and protein rather than on their own.
Name the hunger before you feed it
Before any unplanned snack, wait ten minutes and name which of the three hungers it is. If it is the body, eat a proper meal; if not, deal with the feeling or the cue.
Guard your sleep on weeknights
Keep one fixed bedtime from Monday to Thursday. After a short night, expect a hungrier day and plan a filling meal instead of grazing.
Chapter 04
The last word
Before you go
Pick one step from the action book and do it today. An idea from a book starts to count once it changes what one ordinary day looks like.
Stop arguing with your hunger. Find out which kind it is, and turn the dial down instead.
That is the end of our reading. Where to go from here, or go back to the full The Hunger Code: Resetting Your Body's Fat Thermostat in the Age of Ultra-Processed Food page.
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