Eating during other activities makes it more difficult to feel how full you are

Professor Martin Yeomans, Dr. Sophie Forster and their colleagues have found that when your senses are taken over by an engaging task, you are less likely to realize when you have eaten or drunk enough. The team tested 120 participants, offering them drinks with a lower or higher calorie count and tasks that required more or less of their energy. The paper presenting the response to satiety indices disturbed by perceptual load was recently published in the journal Appetite, on August 12, 2020.

The research team found that participants who were fully engaged in an extremely demanding task consumed about the same amount of food before the drink, regardless of its calorie count. But people who undertook a less demanding task were able to adjust the amount of extra food.

Previous research has shown that when the perceptual demand is high, i.e. the moment when the senses are fully engaged, then the brain filters some of the sensory information. This is the first time that research has shown that the sensory and nutrient indices associated with satiety could be filtered in a similar way.

Professor Martin Yeomans of the University of Sussex School of Psychology said: “Our study suggests that if you eat or drink while your attention is distracted by an extremely attractive task, you are less able to tell how full you are. This is important for anyone who wants to stay healthy: if you are used to eating in front of the TV while watching, say, a captivating thriller or a movie with lots of audio or visual effects, it will be harder for you to realize when you’re full.”

We already know that the feeling of satiety could be affected by the texture and appearance of food, but now we also know that the feeling of satiety depends on how much sensory information is processed at that time in our brains.

This research concludes that a person’s ability to observe when the body feels full depends on how much available attention is “left” in the brain.

The results provide the first evidence that the theory of the task of attention (the idea that a person has a limited amount of sensory information that they can observe) can be successfully applied to eating habits.

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