THE ROUGH GUIDE TO PSYCHOLOGYthat in rich countries, tasty, fatty food is now in far greater abundance
than in previous eras, and it’s this ease of access which leads so many
people to become overweight. In fact, there’s evidence in Britain that
while obesity has risen, average energy-intake since the 1970s has fallen.
This suggests that it’s the second half of the equation – a failure to burn
up enough energy through exercise – that is the greater problem. This
makes sense when you consider the rise of the motor car, the ubiquity
of lifts and escalators, and how many daily tasks – such as washing the
dishes – have become mechanized.
Successful obesity interventions, such as the UK’s MEND (“mind,
exercise, nutrition, do it”) programme, target both eating behaviours
and encourage more exercise. The MEND programme, devised for
children by psychologist Paul Chadwick and paediatric dietician Paul
Sacher, uses enjoyable activities to teach them about healthy eating and
ways to exercise. Particular care is taken to help children who may be
daunted by exercise, for example by not making the activities competi-
tive. When it comes to adults, there’s evidence that setting a specific
time and place to exercise – for example, committing to going running
on Monday and Thursday evenings after work – is more likely to be
successful than making a loose promise to go running more. Formally,
this is known as making “if-then” implementation plans, such as “if it is a
Friday morning, then I will eat some fruit”. A study published in 2010 by
Thomas Webb at Manchester University showed that such plans could be
used to break the usual link between being in a bad mood and behaving
more recklessly, for example by making the plan “if I am in a bad mood,
I will take deep breaths”.
Whether it’s forcing yourself to pound the pavements in the December
drizzle or preventing yourself from reaching for one last cookie, the
crucial factor in your success or failure is self-control. The psychologist
Roy Baumeister at Florida State University has conducted years of fasci-
nating research showing that self-control is a finite resource. The more
you use it up in one situation, the less you’ll have left over in another. In
a study published in 1998, Baumeister and his colleagues asked a group
of participants to resist a plate of cookies and eat the radishes on offer
instead. Compared with a control group who got to eat the cookies, these
abstemious participants persisted for far less time at a puzzle, presented
a few minutes later, which unbeknown to them was unsolvable. Similar
findings have been observed for other acts of self-restraint, such as
suppressing laughter (while watching a comedy film), and for different lab
measures of self-control such as the Stroop test. This latter task requires