Eating while engaged in a perceptually demanding task, like watching TV, makes it harder to recognize feelings of fullness, according to new research from the University of Sussex. Professor Martin Yeomans, Dr. Sophie Forster, and their team discovered that when your senses are absorbed in an engaging activity, you're less likely to adjust your intake of additional food or drink. The study involved 120 participants who consumed either lower- or higher-calorie drinks while performing tasks requiring minimal or high attention.
Participants fully immersed in demanding visual tasks consumed roughly the same amount of chips, regardless of whether they started with a high- or low-calorie drink. In contrast, those with low-demand tasks adjusted their snacking: they ate 45% fewer chips after the higher-calorie drink compared to the lower-calorie one.
Prior studies have shown that high perceptual load causes the brain to filter out sensory information. This is the first research demonstrating that sensory cues and nutrients linked to satiety are similarly filtered.
Professor Martin Yeomans from the University of Sussex's School of Psychology explained: "Our study suggests that if you eat or drink while distracted by a highly engaging task, you're less likely to notice fullness signals. This increases the chance of over-snacking compared to less engaging activities. For TV snackers, gamers, or puzzle enthusiasts watching thrilling content, this means you might miss when you've had enough. We know fullness is influenced by food texture, appearance, and expectations—now we see it also depends on how much sensory input your brain processes at the time."
About the Study
One hundred and twenty participants drank either a low-satiety drink (75 kcal) or a high-satiety drink (272 kcal with thicker texture) while completing low- or high-perceptual-load tasks. Those with low-load tasks and the high-satiety drink reported greater fullness and ate 45% less of the subsequent snack. High-load participants noticed less fullness and overate. The findings show that noticing satiety depends on spare attentional capacity in the brain, providing the first evidence that attentional theories apply to eating behavior.
