How to curb hunger pangs with your mind

There may be a simple way to lose weight using only the power of
thought. You just have to know how, says David Robson.
Eric Robinson has a surprising tool for weight loss. It’s something
we all have, but perhaps don’t use it as much as we’d like: our
memory.
Dieters often feel that they are waging war with their stomachs,
but psychologists like Robinson believe that appetite is formed as
much in the mind as our guts. So much so that if you try to
remember the last food you’ve eaten, thinks Robinson, you can
get thinner without the hunger pangs.
“Lots of research has now shown that subtle psychological
factors can impact how much you eat – but people still aren’t
aware of the influence,” he says. “And that’s important, given the
worldwide obesity problem.” If this is true, how could it work?
The inspiration for this latest thinking comes, in part, from people
with very poor memories, suffering from a deficit known as
anterograde amnesia. You could meet these people and have a
deep, involved conversation – but after 20 minutes they wouldn’t
have the faintest idea who you were. “Something happens to
them, but you come back 20 minutes later and they have no
recollection of it,” says Robinson, who is based at the University
of Liverpool.
Forgotten food
The same is true of the food they eat. One of the key studies
involved a former musician and a former banker, both of whom
had developed anterograde amnesia after a herpes infection
damaged parts of the temporal cortex, the part of the brain that
lays down new memories. They were first given a plate of
sandwiches and cake, which they ate until they were full. The
plates were taken away – only to be returned with more helpings
15 minutes later. While healthy volunteers would tend to feel too
full to eat more, the two amnesic subjects happily filled
themselves a second time . “They forget they’ve had their last
meal, and so if they are offered another one, they’ll eat that too,”
says Glyn Humphreys, at the University of Oxford, who conducted
the study.
Despite their poor memories, the amnesic pair weren’t completely
oblivious to what they had just eaten. In another part of the
experiment, they were allowed to taste a range of foods – rice
pudding, crisps, or chocolate, asked to wait a bit, and then offered
the plates again. Most people, like you or I, seek a variety of
flavours, so we change our preference a second time round – a
phenomenon called “sensory specific satiety”. Like us, the two
amnesic volunteers also felt less tempted by their previous choice
– even though they said they had no recollection of having eaten
it. Their changing preference suggests they didn’t have a problem
with the sensory processing of the dishes – it’s just they couldn’t
form an explicit, conscious memory of the meal. And without that
recollection, they still felt hungry, even when their stomachs were
full.
You might suspect that a healthy brain is smart enough to take
notice of what you’ve eaten, but recent research shows it is easily
fooled. Consider this ingenious experiment by Jeff Brunstrom at
the University of Bristol. His subjects thought their task was
simple: to eat a bowl of soup. Unbeknown to them, Brunstrom had
hooked up a pipe that passed through the table and into the bowl,
which allowed him to top-up some of his subjects’ soup without
them noticing. He found that their later snacking depended almost
entirely on the appearance of the bowl at the start of the meal –
whether it seemed big or small – and very little on the actual
amount he had fed them.
All of which weakens the common notion that hunger is governed
solely by the hormones from the gut. “I’m not suggesting that kind
of signalling isn’t important, but the role of cognition has been
under represented,” says Brunstrom. And in some circumstances
it may be more important.
That could easily have an impact in our hectic, modern lives.
Working lunches are now commonplace in most offices, and
many people watch TV or play with their smartphones and laptops
during evening meals. All of these distractions might affect your
memories of what you’ve eaten. Brunstrom, for instance, asked
subjects to eat with one hand while they played solitaire with the
other . Thanks to the distraction, they struggled to recall the meal,
and pigged out on more biscuits later in the day.
Sensory boost
It is for this reason that the researchers are now looking into
ways of boosting the sensory memory of food. Robinson recently
tested whether a recording, played during a meal, could help a
group of obese women to eat some ham sandwiches more
mindfully. The instructions were simple: the 3-minute clip asked
them to focus on the full sensual experience of the meal – the
sights, the taste, and the smell. A second control group ate with
the pleasant sound of a cuckoo’s melodious calls. As Robinson
had hoped, the people asked to savour their food gave fuller
descriptions later on, and snacked less 3 hours later – consuming
30% fewer calories.
The approach may not work for everyone, but Robinson has other
ideas for alternative techniques; in another experiment, asking
people to consciously remember what they had eaten earlier in the
day seemed to discourage over-eating later on. Your imagination
may even offer a helping hand: a team in Pennsylvania has found
that visualising your cravings, in full detail, seems to trick the
mind into thinking it has actually eaten the snack – reducing
desire and actual consumption.
Robinson is currently working on an app that could remind
someone to recall their previous meals throughout their daily
routine. But despite all these efforts, he points out that we still
need bigger clinical trials to test if memory tricks are really
effective in the ongoing battle with obesity. He’s also concerned
that people might find the procedures tiresome – particularly if
they have to listen to a recording every time they eat.
Promisingly, “attentive eating” does not seem to reduce his
subjects’ pleasure of their meals; on the contrary, they actually
seemed to find it more enjoyable to absorb themselves in the sea
of flavours hitting their tongues. “It’s not unimaginable that
savouring food could actually be a good thing.”
If they work, these memory tricks could therefore offer that rare
thing: a slimming programme that actually enhances your
pleasure in food. And surely that would be one of the more
palatable solutions to the fight against obesity.