Why you keep eating when you’re full
Ever eaten that last slice of pizza, even though you’ve had enough? Or polished off the kids’ leftovers, despite already feeling full? To understand what’s happening – and how to fix it – let’s explore your body’s “stop eating signals”. These are known as satiety signals.
The science of satiety signals
Your body’s satiety signals kick in when your brain senses you’ve consumed enough of the nutrients you need. Your brain takes its cue from sources such as:
1. Stretch signals from your gastrointestinal tract (like your stomach and intestines), which indicate the volume of foods and drinks you’ve consumed.
2. “Satiety hormones”, such as cholecystokinin (CCK) and peptide YY. These are released into your bloodstream when particular nutrients from your digested food come into contact with certain parts of your gastrointestinal tract.
3. Nutrients from your digested food, which pass into your bloodstream and can exert satiety effects directly on your brain
4. Leptin, the hormone primarily produced by adipose (fat) tissue, which stores excess nutrients from your food as fat. The more fat you have in your adipose tissue, the more leptin your adipose tissue releases into your bloodstream, and the more your brain senses you’ve consumed enough of the necessary nutrients.
Your brain puts all of these sources of information into a “satiety algorithm” and, at a certain point, sends you the signal that it’s time to stop eating. This also helps explain why, if you aren’t getting enough of the nutrients you need in your diet overall, you might feel unsatisfied and keep eating, even when you’re full.
I’m eating nutritious foods, so why can’t I stop?
Your body’s satiety signals are easy to ignore. Especially when you’re tempted with a variety of foods, or you feel social expectations to eat. Add an alcoholic drink or two, and it may get even easier to ignore satiety signals. Other factors may include your ethics about not wasting food, and habits like routinely eating dessert – regardless of how you feel.
Eating is about emotions, too
If you’ve ever overeaten while feeling bored, fearful, stressed, lonely, tired or guilty, you’ve found that food can improve your mood (at least temporarily). Some of the hormones and natural brain chemicals involved in satiety signalling have been shown to affect mood.
So, if you regularly keep eating when you’re full, it’s worth exploring possible underlying psychological contributors. Depression, anxiety and stress have been linked to overeating. Take this test to see if you’re experiencing the symptoms.
Post-traumatic stress disorder can also lead to overeating. And no, you don’t have to be a war veteran to have PTSD. This survey has a checklist of symptoms.
Eating disorders such as binge eating or bulimia are also linked to overeating (check this survey of symptoms to see if any apply to you). Having adverse experiences in childhood can also play a role in habitual overeating. Try this quiz if you suspect this may apply to you.
If you suspect psychological contributors to overeating, know there are scientifically proven treatments that can help. For example, depression and anxiety now have well-established treatment pathways. It is possible to treat PTSD with proven therapies. Treatments for eating disorders, including cognitive behavioural therapy, can be effective. Your local healthcare professional can help you find treatment options, and some are free. Below you’ll find a list of additional strategies you may wish to consider:
How to stop eating when you’re full
1. Keep a diary of your satiety signals so you learn to recognise them. Every time you eat, note whether you feel unsatisfied, satisfied or over-satisfied. Aim for “satisfied” every time. If you have an iPhone, you can use the free app I co-designed with Zubeyir Salis (a contributor to this article). Wink by Amanda Salis is based on scientific evidence
2. When you recognise yourself eating to the point of feeling “over-satisfied”, note down what’s happening in your satiety diary or app. Feeling unworthy? Jealous? Irritated? Tired? Or are you simply procrastinating about something? Think about what you really need. Then give yourself more of that instead of food.
3. Choose a nutrient-rich diet with a minimum of ultra-processed foods, and heed cravings for particular healthy foods. This will help you receive the nutrients you need to activate your satiety signals. Use this free, evidence-based quiz to see if you’re on track.
4. Take control over the amount of food served to you. This way, only the amount you feel you can eat will appear on your plate, and you won’t feel tempted to keep eating.
May you always be “satisfied”.
This article was written by Amanda Salis, NHMRC Senior Research Fellow in the School of Human Sciences, University of Western Australia. It was originally published by The Conversation, and has been lightly edited for style and content.