Running on Empty: The Effects of Food Deprivation
on Concentration and Perseverance
Many things interrupt people’s ability to focus on a task: distractions,
headaches, noisy environments, and even psychological disorders. To
some extent, people can control the environmental factors that make it
difficult to focus. However, what about internal factors, such as an empty
stomach? Can people increase their ability to focus simply by eating
regularly?
One theory that prompted research on how food intake affects the
average person was the glucostatic theory. Several researchers in the
1940s and 1950s suggested that the brain regulates food intake in order
to maintain a blood-glucose set point. The idea was that people become
hungry when their blood-glucose levels drop significantly below their set
point and that they become satisfied after eating, when their blood-glucose
levels return to that set point. This theory seemed logical because glucose
is the brain’s primary fuel (Pinel, 2000). The earliest investigation of the
general effects of food deprivation found that long-term food deprivation
(36 hours and longer) was associated with sluggishness, depression,
irritability, reduced heart rate, and inability to concentrate (Keys, Brozek,
Henschel, Mickelsen, & Taylor, 1950). Another study found that fasting
for several days produced muscular weakness, irritability, and apathy or
depression (Kollar, Slater, Palmer, Docter, & Mandell, 1964). Since that time,
research has focused mainly on how nutrition affects cognition. However, as
Green, Elliman, and Rogers (1995) point out, the effects of food deprivation
on cognition have received comparatively less attention in recent years.
Center the title one inch from the top. Double-space
throughout.
Running on Empty 4
The relatively sparse research on food deprivation has left room for
further research. First, much of the research has focused either on chronic
starvation at one end of the continuum or on missing a single meal at the
other end (Green et al., 1995). Second, some of the findings have been
contradictory. One study found that skipping breakfast impairs certain
aspects of cognition, such as problem-solving abilities (Pollitt, Lewis,
Garza, & Shulman, 1983). However, other research by M. W. Green, N.
A. Elliman, and P. J. Rogers (1995, 1997) has found that food deprivation
ranging from missing a single meal to 24 hours without eating does not
significantly impair cognition. Third, not all groups of people have been
sufficiently studied. Studies have been done on 9–11 year-olds (Pollitt et
al., 1983), obese subjects (Crumpton, Wine, & Drenick, 1966), college-age
men and women (Green et al., 1995, 1996, 1997), and middle-age males
(Kollar et al., 1964). Fourth, not all cognitive aspects have been studied.
In 1995 Green, Elliman, and Rogers studied sustained attention, simple
reaction time, and immediate memory; in 1996 they studied attentional
bias; and in 1997 they studied simple reaction time, two-finger tapping,
recognition memory, and free recall. In 1983, another study focused on
reaction time and accuracy, intelligence quotient, and problem solving
