Does it really take 20 minutes for your brain to know you’re full?

Does it really take 20 minutes for your brain to know you’re full?
It’s often said that it takes 20-30 minutes for your brain to register fullness and that you feel fuller after this time than you do straight after eating. This is true, but it isn’t the only way your brain knows how much you’ve eaten, and knowing about the other route from stomach to brain is crucial if you want a reliable guide to how much is “enough”.

Fullness is your gut’s way of telling your brain to stop eating
As we eat, we get increasingly full, as anyone can tell you. Signals from your stomach and gut send information to your brain about what and how much you’ve eaten.

We gain weight in the first place when we ignore feeling full
Most of us gain weight in the first place because we ignore these basic innate signals: we clear our plate out of politeness or finish the ‘sharing’ pack of crisps at the cinema because we’re absorbed in the movie, or we gorge ourselves on chocolate because it makes us feel a bit better when we’re low.

The physical consequences of ignoring our fullness signals
The physical results of eating more than enough depend on how much we have over-eaten. Eating far too much at a meal is soon followed by discomfort, lethargy and possibly nausea. On the other hand, when we eat only a bit more than we need at each meal, we may hardly notice it straight away, but over months and years, our weight creeps up.

The emotional consequences of ignoring our fullness signals
The most common emotional reaction people report in response to over-eating is regret. Within a short time of an overly large meal the wishing-you’d-stopped-sooner begins. And this can lead to a lowering of self-confidence and self-esteem.

An occasional overly large meal is nothing to worry about and won’t lead to weight gain, but habitually large meals will. So if you want to lose weight, and you keep going round in a circle vowing to change your ways tomorrow but then doing just the same when tomorrow comes, you may love learning about how to use awareness of your fullness signals to achieve flexible control over how much you eat.

The amazing benefits of using fullness to guide your eating
When you eat just enough for your body to get hungry by the next meal (or snack time) you allow your body to take a break from constant digesting of food and to begin gut-cleaning and cell repair. Both start to happen after you finish digesting the food you ate and both are good for your overall health.

Stopping at the point of being just full means feeding your body what it needs, and it will respond well to that. Not just with weight loss but with increased energy and often a heightened sense of wellbeing. Throw in the emotional benefits of feeling in control around eating and we’ve found a wonder-drug. Except it’s not a drug at all; it’s simply listening to your body and eating accordingly.

What are the 2 types of fullness signals?
If you haven’t taken much notice of how full you’re getting, it will help to understand that there are two types of fullness signals. One is from the nerve cells in the wall of your stomach and the other is from the hormones released by your gut as food is being digested. The stomach signals detect how much the stomach wall is stretching, which is an indication of the volume of food eaten. These travel extremely fast from stomach to brain. Your gut hormones perform a different job: they register the nutrient content of what you’ve eaten, and these take longer (these are the ones that take about 20 minutes or more) to pass all the information from gut to brain.  It’s no use relying on the slow gut-to-brain signals to tell you when you’ve had enough, because in that 20 minutes or more, you can eat an awful lot of food. With Appetite Retraining my recommendation is that you learn to tune in to the immediate signals from your stomach to tell you when you’ve had enough.

Tuning in to the fullness signals from your stomach
Messages from your stomach wall stretching as food enters are instantaneously sent to your brain by super-fast nerve cell transmission. Because of this, sensations in your stomach change with successive mouthfuls, and it is these you want to learn to take notice of. So next time you’re eating a meal, focus on what you are eating as you are eating it, and see if you can notice the changing sensations in your stomach. It helps if you’re hungry when you begin eating, because then the change from hungry to less-hungry is more noticeable. If you can tell when you’re “just full”, great. This is the point to stop eating and go and do something else for 20 minutes, by which time your brain will have had the slower gut hormone information and you’ll probably feel fuller than you did when you stopped eating.

If you can’t tell when you’re just full, then for now, call what your stomach feels like at the end of your normal sized meal “just full” and your next step (to be covered in a future blog article) is to adjust your meal size and re-calibrate this “just full” point. If you’re keen to get on with doing this before that article is written, the next step is to reduce the size of your meals and call what your stomach feels like at the end of this new sized meal “just full”.

There’s more on the biology of your appetite system in Chapter 2 of my book “How to Retrain Your Appetite” and Chapter 4 gives my 12 practical tips on how to stop eating when you’re just full.

Related article
How to stop eating when you’ve eaten enough

How easy or difficult do you find it to tune in to feelings of fullness? Let me know by emailing info@theappetitedoctor.co.uk and I’ll cover any questions in future blog articles.

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