Understanding how your brain responds to food could be the key to losing weight
The UK’s diet industry is thriving to say the least. More
than half of British adults try to lose weight by controlling their
calorie intake each year. Unfortunately, losing weight is not as easy as
turning down a biscuit, or opting for salad. And even those who have
been successful in their dieting endeavours find it difficult to do.
So why is it that even when we have the best of intentions, dieting is so difficult? Why can’t we control those cravings?
We’ve
all done it: walked past a tasty-looking supermarket stand, or smelled
something delicious and immediately started drooling over whatever treat
is on display, regardless of calorie content or nutrition. Sensory food
cues like these can be difficult to ignore and aren’t just triggered by
taste or smell – advertising or brand logos can tempt us in, too.
When we are hungry, the hormone gherlin stimulates the brain, which
means that we notice food cues more. Researchers have also found that
our brains pay more attention to cues for unhealthy foods – those which
are high in sugar and fat – than healthy foods, when we are hungry. In
studies where pictures of high-calorie foods were shown to participants,
it was found that the cues elicited anticipatory appetite responses,
such as salivation, cravings and a reported desire to eat.
All of this together means that the attention-grabbing properties of
high-calorie foods are likely to present a significant challenge for
individuals who are attempting to lose weight – particularly if their
diet makes them feel hungry.
On a positive note, it may be possible to train ourselves to ignore
tempting cues. One study has shown that participants who were taught to
ignore high-calorie food cues on a computer-based task consumed
fewer snack foods than those who were trained to pay attention to them.
Forbidden foods are more tempting
Dieting often involves “giving up” more pleasurable foods in an
attempt to reduce calorie intake. But if we are asked to avoid eating a
food we enjoy, researchers have found that we will crave it – and even
have a greater desire to consume the forbidden item than if we have not
been deprived.
The more we deprive ourselves of tempting foods, the more we want to eat them
In another study, frequent consumers of chocolate were asked not to
eat any for a week. In this case, the participants found images of
chocolate and other high-calorie food items more salient – the
deprivation had made them want the high-calorie foods more – than the
chocolate eaters who had not been deprived. In addition, when asked to
taste a forbidden food, it has been found that research participants who
have been deprived of it will typically consume more calories.
All of this means that even when dieters attempt to avoid foods that
are pleasurable, the behavioural and cognitive response to deprivation
may inadvertently be creating more temptation.
The “what-the-hell” effect
When trying to lose weight, choices about what to eat and when it
should be eaten are usually constrained by the rules of a chosen diet
plan. But rigid dieting rules are problematic, as any eating behaviour
that does not rely on the physiological signals of hunger increases the
risk of overeating.
Another problem with dieting rules is that only a small violation – a
sneaky slice of cake, for example – is enough to derail the whole diet.
Researchers call this the “what-the-hell effect” – and it has been
demonstrated in a number of laboratory experiments. Studies consistently
show that dieters who believe they have consumed a high-calorie snack –
and so have broken the rules of their diet – will consume more calories
during a later meal than those who do not think they have violated the
rules.
Although in real terms eating a few extra calories is unlikely to
have a major impact on a diet, such lapses can have a bigger
psychological impact. Dieting “failure” is likely to trigger negative
emotions such as guilt or stress, both of which are known to cause
overeating.
So what can be learned from all of this? Diets which require the
dieter to follow rigid rules or forbid them from consuming foods they
enjoy appear to be problematic, as they paradoxically increase the risk
of overeating. Instead, it may be useful for dieters to acknowledge that
humans are inherently drawn to high-calorie foods and that these cues
present the most temptation if we are hungry.
Rising rates of obesity mean that many more of us are turning to
diets to lose weight. However, while there is no perfect diet to help us
achieve our health goals, understanding how the brain works, and
recognising the psychological effects of dieting may help us regain
control in the face of temptation.
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