How to tell fake hunger from real hunger, and why to start eating at 3 and stop at 7 on a hunger scale

Not long after lunch your hand drifts to a bag of crisps, and after dinner something still feels missing, so you open the fridge. In weight consultations I often meet people who struggle with cravings like these that come at any hour.

That is why chapter 2 of the book I co-wrote, Eat to Succeed (published in Korean, 2026), opens with how to read the signals your body sends. The urge to eat is sometimes real hunger, when the body needs energy, but more often something quite different lies behind it. The book says this is not because your willpower is weak or you are lazy.

Around 10 in the morning you feel a little peckish, and as lunchtime nears you start thinking it is time to eat. Real hunger comes on slowly like this. You do not want any one dish, and anything would do. Your stomach may rumble, or it has been three to four hours since your last meal. A normal amount of food leaves you satisfied and the hunger goes away completely.

Fake hunger arrives suddenly, with the thought that you must have that food right now. Because the signal comes from your head rather than your stomach, you crave something specific like chocolate or fried chicken even if you finished a meal an hour ago. However much you eat, you are not satisfied and keep looking for something else, and it is often tied to feelings such as stress, boredom or loneliness. Here are the book's criteria in a table.

If you are unsure, imagine a plain meal of rice and side dishes in front of you instead of the food you crave, and ask whether you would still want to eat. With real hunger, anything feels fine.

Even once you notice it is fake hunger, if you do not know what to do next you end up opening the bag of crisps anyway. The book sorts hunger into six kinds by where it comes from, and what you should do depends on what your body really needs.

Habit hunger and emotional hunger are often locked into a loop. At 10 at night you switch on a drama, open the fridge and cook instant noodles. Switching on the drama is the cue, cooking the noodles is the routine, and the moment of relief is the reward. Repeat the loop and the brain learns the formula.

The book says to keep the cue and the reward and change only the routine in the middle. If what the crisps really gave you was not a full stomach but comfort that let the day's tension go, fill that slot with another activity that gives the same comfort. Do not buy crisps at all, and delete the delivery app. Having to reinstall it gives you one more chance to stop.

There is a reason sweet food calls to you on stressful days. Sweet, fatty food stimulates the brain's reward system and briefly lifts your mood. When the stress hormone cortisol is high, appetite rises too and you reach for sweet and fatty food.

One study measured this in the lab. In the US in 2001, 59 healthy premenopausal women took part on two different days, once in a stressful session and once in a control session, and what they ate afterwards was measured. Women whose cortisol rose sharply under stress ate more calories than those whose cortisol rose little on the stress day, but about the same on the control day. The high cortisol group ate more sweet food on both days, and the more their mood worsened, the more they ate.

This study watched 59 women in a lab for one day each, so it does not show whether anyone actually gained weight. Still, it is hard to put sweet cravings on a stressful day down to willpower alone.

Thirst is also easy to mistake for hunger. The brain often confuses the two signals and reads a need for water as a want for food. The book suggests drinking a glass of water when you feel hungry and waiting 10 minutes. It also recommends a glass of water with every meal and snack, and at least eight glasses a day.

Hunger from a nutrient shortfall or from tiredness does not go away by eating more. If you get your calories but not enough protein and minerals, the body keeps telling you to eat because what it needs has not arrived yet. Include protein at every meal and fill half your plate with vegetables at lunch and dinner. If you crave sweet and fatty food after a short night, what your body really needs is not calories but deep sleep and rest.

In trying to filter out fake hunger, some people end up holding out against every hunger. Skip breakfast, get by on a scrappy lunch and hold on until dinner, and by evening you are dizzy, shaky and irritable. In English this is called being hangry, hungry and angry at once. You have gone without food so long that you want to eat anything fast and cannot control how much. When hunger peaks, the limbic system that drives instinct takes over from the frontal lobe that handles reasoning and orders you to eat a lot, now.

The book says hunger is not 0 or 100 but a continuous scale. On a scale from 1 to 10 it looks like this.

• 1 Extremely hungrydizzy, shaky and irritable. You have gone without food so long that you cannot control how much you eat.
• 3 Hungryenergy is dropping, your stomach rumbles and you think about food. A good time to start eating.
• 5 Neutralneither hungry nor full, and comfortable.
• 7 Satisfiedno longer hungry, and comfortable. A good time to put your spoon down.
• 10 Overfullyou have eaten so much you feel ready to burst and can hardly move.

The three-hour gap between meals in the 3.6.9 diet ties in with this scale. If you eat ahead of time instead of going hungry until dinner, you can start dinner at a moderate 3 or 4 without extreme hunger.

Some days you eat without noticing you are full and only realise you overate when you get up from the table. Food has to move from the stomach to the small intestine and hormones have to be released before the signal reaches the brain, and that takes at least 20 minutes. Finish a bowl in five minutes and you have already eaten a lot before the brain gets the message.

The signs of fullness are subtle. The book puts it this way: the first few bites are heaven, but as you keep eating the taste becomes less intense, and that is the first sign. You slow down without trying, lose interest in the food and want a drink of water. A sigh or a deep breath means your body wants to rest.

To catch these signs you need to eat slowly. These are the methods in the book.

• 20-minute timerset at least 20 minutes for the meal and eat slowly until the timer ends.
• Put your chopsticks downput them down after every bite.
• Chew 20 times or morechew until the food is soft as porridge and focus on the taste.
• Screens offturn off the TV and phone and pay attention to what you eat.
• Pause halfwaywhen you are about half done, put your spoon down and check where you are on the hunger scale.

One study compared whether eating slowly really means eating less. In the US in 2008, 30 healthy women with an average age of 23 came in twice and ate as much as they wanted, once quickly and once slowly. On the slow day they ate 579 kcal on average, less than the 646 kcal on the quick day, and drank more water. Even though they ate less, they felt fuller at the end of the slow meal.

This was 30 young women of normal weight eating one meal each time, and the difference was a little under 70 kcal per meal. It is not a study that shows eating slowly on its own leads to weight loss. Still, they ate less and finished more satisfied, which helps when you are trying to stop at 7.

Many people skip breakfast because they are not hungry in the morning. The book says this may be the body having adapted to going without. A body used to irregular meals does not send hunger signals on time.

In that case I recommend eating at set times rather than waiting until you feel hungry. In the first week of 3.6.9, set five phone alarms a day and when one goes off, eat at least a light snack such as a banana or yoghurt. If you are not hungry, a very small amount, like a few spoonfuls of yoghurt or a few nuts, is fine. The book says that after about a week the body adapts and you start to feel hungry naturally without the alarms.

On the other hand, if you already eat three meals on time and do not binge, there is no need to go up to five. The book also says that if you usually eat three regular meals and do not overeat, there is no need to increase to five.

Jotting down for a few weeks what you ate and how much energy you had afterwards helps you find the meals that suit you.