We may be hardwired to eat fatty, calorie-rich foods, but that does not mean we are slaves to our primal instincts, says Clodagh Finn
WHY do we eat unhealthy foods? We know we should eat less fat, cut down on sugar, and exercise more, and, yet, we are getting fatter.
One in four Irish children is overweight, according to Safefood figures, and the Department of Health says that just 40% of Irish adults are a healthy weight.
Healthy-eating guidelines and public information campaigns have failed to modify our eating behaviour.
The problem, says obesity researcher, Dr Stephan J. Guyenet, is that the approach overlooks one crucial aspect of eating behaviour — a hungry human brain is hardwired to crave calorie-rich food.
“We know that obesity is caused by more energy entering the body than leaving it, but that doesn’t get us that far in thinking about what it is and what to do to reverse it,” Dr Guyenet tells Feelgood.
To understand why we make seemingly involuntary food choices, the Seattle-based scientist became the guinea pig in his own laboratory experiment, which yielded striking results.
He skipped breakfast and lunch, then cycled to the University of Washington, in Seattle, to ensure that he would be hungry, before undergoing a functional MRI scan, a test that aims to understand how the brain influences what we eat.
While lying inside the scanner — which he interestingly compared to a “giant white doughnut” — Dr Guyenet was shown images of high-calorie foods (pizza, crisps, pastries), healthy foods (celery and apples), and non-food items (shoes, a car).
The test results were unequivocal: “My hungry brain wanted food.” And it wanted a lot of it. However, the images of fruit and veg failed to register any brain activity.
What Dr Guyenet’s brain was telling him was to get a high-fat snack, immediately.
He wasn’t surprised. Research by his colleague, Ellen Schur, had already shown that people, when hungry, seek out high-fat, calorie-dense food, rather than healthy food.
We are hardwired to look for the foods that will release the so-called feel-good chemical, dopamine, in the reward centres of our brains.
But, says Dr Guyenet, celery sticks and lentils just don’t cut it. The brain is looking for foods that combine fat and starch — chocolate, pizza, ice cream, for example — and which will deliver an extreme reward.
“People don’t appreciate that what is happening on an unconscious level is having an important impact on our behaviour,” he says.
In fact, the human decision-making process is less conscious, and far more impulsive, than most of us believe, according to psychology and neuroscience.
While having a calorie-seeking brain was an asset to our hunter-gatherer ancestors, it is a liability in the western world, where a dizzying array of foods are available on every supermarket shelf.
There are a staggering, 44,000 different items on display in the average supermarket, according to the Food Marketing Institute.
The range of foodstuffs available to modern hunter-gatherer cultures is much more limited and, quite often, those communities depend on a single plant, or food source, for at least half of the year.
Also, nothing in nature, with the exception of honey, has the kind of highly concentrated levels of sugar, salt, or fat that are found in the processed foods that rev up our brain’s reward centres.
Anthropologist, Kim Hill, told Dr Guyenet that the Aché hunter-gatherers of Paraguay, and the Hadza of Tanzania, will often binge on honey, eating up to a litre of it at a time.
But, says Dr Guyenet, that doesn’t happen every day; not even every other day. He says those communities are struggling to get calories and will gorge when they have the possibility.
While most of us don’t binge to that extent, we have the same instincts, which push us a little further than we want to go.
“The only way to truly understand overeating is to understand the brain,” Dr Guyenet says, explaining his reasons for writing The Hungry Brain (€20.99, Penguin), a book that explores the science of overeating.
“Overeating and obesity are caused by a mismatch between ancient survival circuits in the brain and an environment that sends these circuits the wrong messages,” he says.
If you want an example of a ‘wrong message’, drive into any garage forecourt. In the garage shop, you can gulp down a cappuccino (150 calories) and munch on a large muffin (up to 450 calories) — almost a third of your recommended, daily calorie intake — while buying the morning paper.
Dr Eva Orsmond, whose new health series for RTÉ is due out next month, says our growing affluence has also had an impact on how we eat.
She doesn’t believe in middle-age spread, either. “It’s not our age; it’s because we are doing less. We are more comfortable; we can afford more cappuccinos. Or, there’s wear and tear on the knees or our energy levels are lower.”
She says Irish people consume four times more sugar than the recommended amount (six to nine teaspoons), but the problem is not just sugar.
Dietician, Orla Walsh, says the reason Irish people are overweight or obese isn’t entirely due to sugar — we simply eat too much: “A big part of this is that we eat calorie-dense foods. The focus needs to be on encouraging people to eat foods that have fewer calories per bite,” she says.
“If you ask a person to write down a list of rewards, they would happily, and easily, write a list of specific foods that they use to reward themselves. Ask them to write a list of non-food or drink-based rewards, and they struggle,” she adds.
But, she says, we are not powerless and can maintain a healthy weight by exercising regularly and eating enough protein at each meal.
And, yet, the Irish are at the top end of the European obesity scale. According to a study in the Lancet medical journal, Irish men have the highest body mass index (BMI) in Europe — a measure of obesity — while Irish women rank third.
Heather Leeson, director and senior nutritionist, Glenville Nutrition Ireland, says the overwhelming availability of food, especially less-than-healthy choices, is a real issue.
“However, in addition to availability, many of our food choices are made unconscious, habits established over many years,” she says.
“For example, the habit of rewarding ourselves with sweet treats, or always having a couple of biscuits with a cup of tea.
“Having a couple of biscuits, occasionally, is not a big issue, but having them every day can account for a weight gain of two or three pounds a year, or a stone over four to five years.”
One good way to outwit the hungry brain is to make sure you never allow yourself to get over-hungry. “If your meals are further than four hours apart, we recommend having a small, healthy snack, such as a piece of fruit and a handful of nuts,” she says.
While the food industry might not fully appreciate the deep-seated brain mechanism that makes us look for fat, sugar, and salt in food, it is expert at making food look seductive, so that it activates our drive to eat it.
At least adults are aware that advertising is designed to persuade, but children are not so aware.
Studies show children are particularly vulnerable and respond to TV food advertising by changing their food choices and by eating more.
One 2004 British study, by Prof Jason Halford and colleagues, found that overweight children were even more susceptible: they remembered more food adverts than toy adverts and were more likely to be influenced by them to eat more.
Regulating advertising, and in particular advertising directed at children, is part of the solution, but Dr Guyenet says the most effective path to stopping obesity is to change the environment. The omnipresence of food cues in that environment is a point that is taken up by professor of marketing at UCC, Mary McCarthy. “It is quite difficult to avoid food,” she says, providing a simple example: from her office, she can see a food service; two floors down, there is another one and she only has to walk 100m in another direction to find yet another.
Modern society and advances in technology have eliminated the effort and energy that was once involved in getting food.
While that has created significant challenges, she says simple mechanisms and policy shifts can help to change human behaviour.
For example, she says, there was a time when restaurants put salt on the table. They are less inclined to do so now. While it is still available, customers have to ask for it, which they are less likely to do, unless they really want it.
“Putting little hurdles in place makes people stop to think about it,” McCarthy says.
If we have an unconscious, physical instinct to seek out energy-dense foods when hungry, we also make a series of unconscious decisions, in our daily lives, that shape our eating behaviour — for example, buying the easier, but less healthy food option, taking out the biscuit jar when the kettle boils, associating pizza with an evening chill-out in front of the TV.
Small adjustments, or nudges, can change the kind of unhealthy behaviour that has led to a consistent weight gain over the last number of decades.
For example, people will eat almost every sweet in a bowl if it is beside them, but if the bowl is moved a little further away, they are less likely to dip in, as it involves effort.
She cites the self-service ‘all you can eat’ buffet as a good example of how you can unconsciously shape consumer behaviour.
The buffet providers want to give the impression that they are offering great value for money, yet they don’t want people to eat too much, as that will deplete their profits.
A number of small adjustments stop people overeating.
For instance, if the plates are positioned at the end of the buffet, people eat less, as they survey all that is on offer on the way to getting a plate and then they make specific choices. If they are seated further away from the buffet or with their backs turned to it, they are less likely to go back for second helpings.
The human brain is hardwired to eat sugar and fat when hungry, but that doesn’t mean we are doomed to overeat. By making some smart moves, we can outsmart our most deep-seated instincts.
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