HOW TO CURB OBESITY

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.