A SANDWICH at your desk, eaten in bites as you type on the keyboard. Tea and biscuits while absorbed reading the newspaper. A slice of cake in front of a film. For many of us, meal times have become just another to-do job, and the temptation is to multi-task.
At the back of our minds, we suspect it’s not ‘ideal’ to eat while working, or walking, or watching TV – slightly slovenly, perhaps. In fact, the latest research shows you’re not just at risk of smearing chocolate on the sofa or getting crumbs in your keyboard – eating this way could be one reason you’re putting on weight.
Intriguingly, it’s not simply because your brain is distracted so you forget you’ve eaten and so eat more – but because your body itself doesn’t register the food.
A new study from the University of Sussex has shown that, when your attention is completely absorbed by something other than what you’re actually eating – for instance, working hard at your computer – you fail to sense the calories in any food you’ve consumed.
In the study, published just a fortnight ago in the journal Appetite, 120 volunteers were fed a high or low-calorie ‘smoothie’ through a tube into their mouth while performing either a very complex on-screen test or a less challenging version of it.
The volunteers, who didn’t know which version of the shake they’d had, were offered crisps a few hours later and the number they ate was then counted by researchers.
Among the group who had performed the easier task, requiring less of their attention, those who’d been fed the high-nutrient drink ate far fewer crisps than those given the low-calorie smoothie. In other words, they had somehow registered that they’d had enough to eat.
But when the group engaged in the complex task were fed a high-calorie smoothie, they ate just as many crisps – if not more – than those given a low-calorie smoothie.
This is significant, because "normally we find people eat less after having had a high-nutrient meal than they do after a low-nutrient one," explains Martin Yeomans, a professor of experimental psychology and one of the authors of the study.
"That sounds blindingly obvious, doesn’t it, but the point is, the participants don’t know what they’ve taken in, yet they are able to sense this hidden nutrient difference if they are focused on what they are eating," he adds.
"In this latest study, we saw that when people were slightly distracted but doing a task in which their attention wasn’t fully engaged, they were still able to notice this hidden calorie difference. Their body was sensing those nutrients.
"However, we saw that if your capacity for attention is completely used up doing a demanding task, you become unable to sense those nutrients. What this means in the real world is that if you’re really busy and eat something, you essentially don’t register that you’ve ingested it, creating a risk that you will over-consume."
A similar result was seen in a study at the University of Surrey in 2015, where participants who ate a cereal bar ‘on the go’ – ie while they were walking – later ate more than those who had eaten the bar either as they were watching television (a minimally distracting episode of Friends) or talking to a friend.
Jane Ogden, a professor of health psychology who led the Surrey study, said: "We think this is because walking is a powerful form of distraction, which disrupts our ability to process the impact eating has on our hunger?.?.?.?
"When we don’t fully concentrate on our meals and the process of taking in food, we fall into a trap of mindless eating, where we don’t track or recognise the food that has been consumed."
What’s fascinating is that it’s not as simple as forgetting that we’ve eaten – it’s that our bodies have entirely failed to register it. How our bodies sense what we have eaten and determine hunger or satiety is not yet fully understood.
However, pieces of the jigsaw include the release of hormones from the gut which transmit messages to the brain, as well as? our blood sugar levels and simple physiological signs, such as whether your stomach feels as though it is ‘full’.
"There are a lot of nutrient sensing systems in the gut," explains Professor Yeomans. "For example, we know that taste receptors exist throughout the gut system. So just as you can taste a sweet sensation in your mouth, there are the same sorts of sweet detectors in your stomach and intestine.
"Now, your brain doesn’t say, 'Oh, my stomach feels sweet,” but it must be picking up some signal produced by the presence of sugar molecules in your stomach. And they contribute to that sense of fullness or hunger.
"If you’re not able to detect those subtle internal signals, it becomes difficult to regulate your appetite," he adds.
This all seems to support the popular concept of ‘mindful eating’ to help curb overeating. The technique requires you to focus on the food, appreciating all of its flavours and textures, eating slowly and savouring each bite without distractions.
"All too often eating forms part of some elaborate multi-tasking, and we rarely give it the attention it deserves," says dietitian and nutrition consultant Laura Clark (lecnutrition.co.uk). "But paying attention can help to break the cycle of overeating that affects many people."
Our body "is very sophisticated", she says. "If we actually listen to it, we are able to tune into hunger and fullness signals, which work in exactly the same way as other bodily functions we think less about – for example, temperature regulation or emptying our bladder."
If eating without distraction is the best thing for us, does this mean that the old-fashioned ideal of creating family cohesion by having a meal together at the dining table is misguided?
Not at all, says Prof Yeomans – rather than distracting you from your meal, the typical family dinner table interaction will lead to greater appreciation for the food.
"It’s a kind of mindful eating, and a recent scientific review showed that every published study on mindful eating has shown it has positive effects.
"You will almost certainly be saying, 'Oh, this tastes good' to the person who cooked, or a child might say, 'I don’t really like the beans, do I have to eat them?' All these are acknowledgements that you’re noticing what you’re eating.
"Preparing food and eating as a family can help us learn what the French call 'elegant sufficiency'. This idea is that you serve a sensible portion of absolutely delicious-tasting food, then thoroughly enjoy eating it, with the aim of feeling satisfied but not stuffed."
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