You might have heard that it takes 20 minutes for the brain to register that the stomach is full. But this is only the approximate amount of time in minutes that it takes the brain to react. Just how long it takes your brain to respond depends on several factors.
20 Minutes to Feel Full?
The amount of time it takes for your brain to register that your stomach is full can vary, and it may take up to 20 minutes. It depends on many factors.
"Because of the cornucopia of signals, hormones and mental and physical reactions involved with fullness, it's impossible to come up with a one-size-fits-all answer to how long it takes for the brain to register fullness. However, there is some truth to the statement that it may take the body up to 20 minutes to feel full," says Jonathan Purtell, RD, a registered dietitian with Lenox Hill Hospital in New York City.
Once you start eating, your body gets busy digesting the food and communicating to your body about it. "If we break down the meaning of feeling full, the two main factors include the stomach's overall capacity to hold food and the body's ability to start signaling satiety," Purtell says.
"Satiety signals are processed about 20 minutes after your first bite, but if you do feel full before this, it's likely that your stomach has reached capacity. During that 20-minute period, the body is producing gastric enzymes and hormones to not only help digest food, but also start signaling satiety cues to the brain," Purtell says.
Satiety, or feeling full, happens as a result of many body signals that are triggered when food or drink is ingested, digested and absorbed, according to the British Nutrition Foundation. These signals are impacted by various factors such as your:
- Belief regarding how filling the food or drink will be.
- Sensory experience.
- Expansion of the stomach.
- Hormones, which are released while food is being digested and absorbed.
The Foundation says that these signals coalesce in areas of the brain responsible for controlling the intake of energy. While you can feel your stomach becoming fuller as you eat, it takes time for all of the signals to reach your brain.
Under normal circumstances, this sensation makes us stop eating and thinking about food for a number of hours, according to Alberta Health Services. The feeling of fullness is also influenced by your blood sugar levels, the hypothalamus (area of the brain that produces hormones related to hunger) and the physical presence of food in your stomach and intestines.
The Gut-Brain Connection
The feeling of fullness is dictated by a stomach-brain connection through which constant communication takes place between the enteric nervous system (gastrointestinal tract) and the central nervous system (brain), Purtell says.
"Generally, the body starts to produce ghrelin, known as the hunger hormone, and signals to the brain that food or water is required," Purtell says. "Once food is ingested, the production of enzymes and hormones leads to the cessation of ghrelin production and starts to send satiety signals to the brain. There are multiple ways our stomach signals to our brain that it's full — the stomach also contains stretch receptors, which monitor the total capacity of the stomach. Once these receptors reach a certain level, they signal to the brain that the stomach is full."
However, Purtell says, according to new research, the stomach and the rest of the gastrointestinal tract act like a second brain. "What we're learning is that this conversation isn't as simple as hunger and satiety," he says. "In fact, it involves a whole cascade of mental and physical reactions. For example, at times of anxiety or stress, we may experience stomach discomfort. This is when some people experience that butterfly-like feeling."
How to Use This Information
Being aware of your own internal cues can help you better pace yourself at meals. If you're reading this because you're concerned about overeating, Purtell recommends that you:
- Focus on being adequately hydrated throughout the day.
- Make sure to include high-satiety foods in your diet, such as those high in protein and/or fiber during meals.
- Take your time to eat.
"Not only will slowing down the eating process reduce the chance of overeating, you may also feel more satisfied after each meal," he says.