Transcript Feast or Famine: The Psychology of Eating

FEAST OR FAMINE?
THE PSYCHOLOGY OF EATING
Professor Glenn Wilson, Gresham College, London
TOO LITTLE, TOO MUCH
Eating is a major problem.
In the Developing World many
people die because they don’t have
enough food.
In the West, people die more often
because they are surrounded by too
much. Either they overeat and
become susceptible to obesityrelated diseases or they starve
themselves by compulsive fasting
in the midst of plenty. Anorexia is
a disease of the affluent middleclasses, not the poor.
Around 10% of teenage girls in the
UK have some kind of eating
disorder and there has been a 13%
increase over the last decade
(Micali et al, 2013).
WEIGHT STEREOTYPES
Popular belief that people are
responsible for their own body
shape.
Negative traits are commonly
ascribed to overweight people
which “explain” and blame them
for their condition (e.g. lazy,
undisciplined).
Some negative stereotypes also
attach to slim people (e.g. vain,
bitchy, mean).
Yon Cassius has a lean and
hungry look . He thinks too
much - such men are dangerous.
(Julius Caesar).
Survey of 1800 women aged
18-40 (Glamour, 2012)
GENETIC INFLUENCE
Body weight depends on interplay
among many genetic and
environmental forces.
Twin studies show 40-70%
heritability (Herrera et al, 2011).
Many genes involved: 40+ locations
so far implicated in various appetite,
energy storage and metabolism
processes.
The best-known “obesity-risk” gene
(FTO) is associated with a failure of
satiation after eating (Karra et al,
2013).
Epigenetics (gene expression effects
without DNA alteration) also have
impact.
All of this makes control of weight
very difficult.
Though often thought of as “faulty”
the survival advantage of obesity
genes in lean times is obvious.
EATING HABITS
Eating, drinking and exercise
styles relate to obesity in
complex ways. In a study of 1356
UK adults (Wilson 1985), body
weight was associated with lack
of exercise, overall food intake
and eating in response to
emotional stress. The latter
seemed to reflect difficulty in
maintaining dietary restraint in
constitutionally heavy people.
Diets tend to collapse at times
when people are lonely, stressed
or frustrated.
Sugar consumption and daily
drinking were unrelated to body
weight or health problems;
healthy people perhaps allow
themselves more luxuries.
COMFORT EATING
When a sports team loses,
their fans eat more junk
food the next day.
Consumption of high
calorie food increases on
Monday in a city whose
NFL team has lost on
Sunday, whereas it
decreases in the victors’
city (Cornil & Chandon,
2013). Effect is greater in
cities with the most
committed fans, when
opponents are equally
matched and defeats
narrow. Similar findings
with French soccer fans.
A self-affirmation
procedure (ranking and
discussing core values)
showed promise in
countering the effect of a
sports loss.
PERSONALITY AND BMI
Impulsivity is the strongest
personality correlate of
weight gain.
People get gradually heavier
with age but those in top 10%
for impulsivity averaged
24lbs more than those in the
bottom 10%.
Extravert people were also
heavier; Conscientious and
Agreeable people tended to
be thinner.
Those high in novelty-seeking
were less successful in a
weight management
programme (Cloninger et al
2007).
Diet and exercise require
commitment and restraint,
which are lacking in certain
individuals.
Longitudinal study of 1,988 adults in
Baltimore (Sutin et al 2011).
HUNGRY SHOPPERS
People who shop in a
supermarket when hungry
don’t buy more food but do
buy more high-calorie
products (Wansink & Tal,
2013). Subjects food-deprived
for 5 hrs chose 5.72 high
calorie products, vs 3.95 for
sated controls. Interpreted as
an effect of food insecurity.
Suggested that weightwatchers should have a snack
before shopping or go after
lunch. Good to take a list
(ideally not children).
THINKING YOURSELF FULL
It is possible to trick people
into feeling less hungry.
Brunstrom et al (2012) used a
soup bowl that would covertly
refill or lower its quantity as
people ate from it. Immediately
afterwards, self-reported
hunger was based on how
much they had actually
consumed. However, after 2/3
hours “hunger” went with how
much they thought they had
consumed (memory of bowl
size).
Food labels emphasising
“light” and “diet” ingredients
may be counterproductive,
making us think we are less
satisfied (so we eat more later).
People shown a large quantity of
fruit that has supposedly gone into
their smoothie feel more “full”
afterwards (Brunstrom 2012).
TV MAKES YOU FAT
Watching TV
contributes to obesity in
several ways.
Viewers are sedentary
for long periods.
If they snack while
watching they lose track
of how much they have
had and consume more
later (Mittal et al, 2011).
If the content of the TV
programme is foodrelated or depressing
they will eat even more
of any food that is handy
(Laran, 2013).
SLEEP DEPRIVATION
Late bedtimes allow
more waking time for
eating and late-night
snacks tend to be more
fattening (Spaeth et al
2013).
Also, sleep loss is
apparently stressful.
Decreased activity in
cortical evaluation
regions of the brain
(frontal and insular
cortex) together with
increased amygdala
activity prompts desire
for high-calorie,
fattening foods (Greer et
al 2013).
SOCIAL INFLUENCES
People eat more in company than
when alone. The social facilitation
effect is stronger for friends/family
than with strangers. Several
reasons: (1) Eating is a shared
activity that consolidates social ties.
(2) Meal lasts longer, giving more
time to eat. (3) Conversation is
distracting, so self-monitoring is
impaired (c.f. TV viewing).
Eating with friends: +18% calories,
Viewing TV: +14% (Hetherington et
al 2006).
People dining in twos tend to match
their intake. Women eating with
men eat more daintily than by
themselves or with other women. Women eat less when men are present than with
other women. Men not affected by company.
(Young et al 2009).
OBESITY CONTAGION
Social network analysis (Christakis & Fowler, 2010) indicates that obesity spreads like
a virus. Friends have similar body build – neighbours do not. Norms for acceptable
body build, portion size, etc. may be passed among friends to influence weight.
PRIMING INDULGENCE
Seeing overweight people can
lead us to eat more (Campbell
& Mohr, 2011).
People walking through a
lobby answered survey
questions that included a
picture of either an overweight
or normal-weight person.
Afterwards they helped
themselves to a bowl of
wrapped sweets as a “thank
you”.
Those who saw the larger
model took more sweets than
the one who saw the thinner
image (means of 2.2 vs 1.4).
Four other studies confirmed
this anchoring (reassurance?)
effect.
Sticking overweight images on the
fridge door may have a reverse effect,
shifting the idea of what is normal.
CONTROL STRATEGIES
Many behavioural tips for controlling
food purchase and consumption have
been offered:
(1) Don’t buy jumbo packs, multi-buy
offers, snacks/sweets, meal-deals.
(2) Store tempting foods well-packaged
& out of sight/reach (not in office
drawer or glove box of car).
(3) Keep a healthy option to hand
(fruit or unsalted nuts).
(4) Drink water rather than fizzy and
sugary drinks.
(5) Decide serving size in advance.
(6) Take your time when eating.
(7) Don’t eat while doing other things
Frequent use of such strategies
discriminates normal from overweight
people but not overweight from obese
(Poelman et al, 2013).
SELF-MONITORING
A key element in behavioural
weight management
programmes is some form of
recording of eating patterns,
weight or exercise (e.g.,
weighing self first thing every
morning, or regular waist
measurement).
Paper diaries, websites and
phone aps can be helpful.
Does not seem to matter exactly
what is monitored provided it is
done on a regular basis (Burke
et al, 2011).
Motivational, and may detect
patterns, giving early warning.
SLIMMING GROUPS
Slimming classes like Weight
Watchers are more successful
than individual weight-loss
programmes set up by doctors
(Pinto et al, 2013).
These are behaviourally
oriented: focus on changing
eating habits and promoting
exercise.
Usually led by trained peer
counsellors who have achieved
their own weight loss.
Social context contributes to
motivation and makes the
treatment affordable.
ANOREXIA
Pathological dieting, combined with
denial of any problem.
Most common in young women aged
12-19 (10x F/M).
Become fearful of fat, obsessed by
food/calories, develop rituals around
eating/mealtimes and avoid food
deceitfully (e.g., pushing food around
plate and hiding it in napkin).
Some follow pro-anorexia websites
and smoke/take drugs rather than eat.
May be maintained by endorphin highs
evoked by starvation (Brindisi &
Rigaud, 2011).
Can be life-threatening; highest
mortality of any mental illness (5-10%
for every decade untreated). However,
most (50-70%) get better within 2ys.
.
BODY IMAGE DISTORTION
Anorexics overestimate their size.
See themselves as fat (or claim to
so as to justify food-avoidance?)
Asked to adjust a mirror until the
reflection is accurate they make
themselves fatter than they really
are.
May turn sideways to go through
a doorway they would
comfortably fit head-on.
Misperception applies
specifically to themselves, not to
others around them (Guardia et
al, 2012).
If not thinking themselves fat,
may be proud of their bony form,
believing themselves to be
attractive.
RETREAT FROM PUBERTY
Anorexia is strongly associated with
onset of puberty (which gets earlier).
Trigger may be observation of bodily
changes like breast & hip
enlargement, which arouse fear they
are getting fat.
A more psychoanalytic idea is that
anorexia is specifically focused on
avoidance of menstruation and a fear
of growing up and assuming adult
responsibilities. Carbohydrate intake
seems geared to keep weight just
below the level where cycle would
commence.
Recovering anorexics who regain
normal luteinising hormone responses
to LHRF show greater adolescent
conflict on a repertory grid measure
(Miles & Wright, 2011).
PERSONALITY AND ANOREXIA
A particular set of
personality traits is
associated with anorexia
(introversion, anxiety,
perfectionism, OCD).
Often pride themselves in
self-control.
A connection with autistic
spectrum disorders has
been suggested (“female
Asperger’s”).
Some of these
associations diminish
with recovery, so may be
a result of the starvation
effects on the brain rather
than pre-existing causes
of the disorder (Cassin &
von Ranson (2005).
THE ANOREXIC BRAIN
When people look at body
images, input is via the medial
occipital area (mOC), then the
fusiform body area (FBA) to the
extrastriate body area (EBA).
Suchan et al (2013) found a
lower density of neurons in the
EBA in anorexic patients and
reduced input from FBA. This
weakened connectivity between
FBA and EBA might account for
the development of anorexia, or
could be a result of it.
Other studies have shown
increased activity in emotional
brain centres in response to food
and body stimuli relative to
controls (Zhu et al, 2012).
SPRING BIRTH
Anorexia is more
common in those born
March to June (Northern
Hemisphere). A similar
relationship applies for
major depression.
Probably due to vitamin
D deficiency in the
mother during winter
gestation. Allen et al
(2013) found Australian
mothers with low
vitamin D (measured at
18 wks pregnant) were
more likely to have
teenage daughters with
eating disorders.
Data from meta-analysis of 4 UK cohorts,
N= 1293 anorexics (Disanto et al 2011).
MANOREXIA
Concern with muscularity may
be a male equivalent of female
anorexia.
Field et at (2013) found 9.2% of
male adolescents had high
concerns re muscularity (only
2.5% concerned about thinness).
Often leads to use of
supplements (e.g. growth
hormone, steroids) harmful to
health.
Those concerned with thinness
more prone to depression than
those with muscularity
concerns.
Body image problems in general
more common in homosexual
men.
BULIMIA
Binge eating of high calorie food is
followed by purging or self-induced
vomiting.
Stomach acids can damage throat,
cause tooth decay & bad breath.
Also more common in young
women but weight likely to be
normal (Princess Diana).
Men not immune (John Prescott,
Elton John).
Whereas anorexia goes with anxiety
and constraint, bulimia relates to
impaired self-regulation and impulse
control (Marsh et al, 2009).
Comorbid with borderline
personality disorder, substance
abuse, shoplifting, self-mutilation
and sexual disinhibition.
TREATMENT
May be necessary at first to
hospitalise and force-feed.
CBT (modification of beliefs &
attitudes) is favoured treatment but
co-operation not always forthcoming.
Important to look at motivation and
ensure readiness to change.
May need to treat co-occurring
problems such as anxiety,
perfectionism, depression, substance
abuse and attention deficit.
Drugs (e.g. SSRIs) may help,
especially if depression is involved.
Some experimental work with deep
brain stimulation, but this is a last
resort.
The Maudsley Model (Le Grange,
2005) involves the family in
treatment, e.g., teaching parents how
to supervise meals. However, family
attitudes are sometimes part of the
problem.
FAD DIETS
Diet plans are a major industry.
Usually work by excluding certain
types of food, thus reducing total
calories if maintained long-term
(Pagoto & Appelhans, 2013).
Intermittent fasting also limits
calorie intake, unless there is
“catch-up”.
Compliance is poor because
hunger increases and body goes
into distress mode (release of
stress hormones and lowered
metabolism). When the diet stops
there is rapid rebound to baseline
or beyond.
Mostly unhealthy compared with
balanced diets and exercise.
Breatharianism (living only on
nutrients of sun and air) is most
effective but eventually fatal.
SKINNY MODELS
Models in women’s magazines are
often airbrushed and unrealistic.
Catwalk models are pressured to be
dangerously thin so as not to distract
from the clothes.
Proliferation of unhealthily thin
models in the media has been linked
to body dissatisfaction, substance
abuse (smoking/heroin), eating
disorders and depression (Grabe et al,
2008).
However, only women high in
neuroticism suffer harmful effects of
thin models (Roberts & Good, 2010).
Long exposure to thin-ideals can
sometimes increase body satisfaction
by prompting dieting and exercise
(Knoblock-Westerwick & Crane,
2012).
If Barbie were real she would
have a 16in waist and be infertile.
HELP FOR THIN WOMEN