People who gain weight are more likely to give in to
temptations but also are more thoughtful about their actions, according to a
new study published in Psychological
Science, a journal of the Association for Psychological Science.
To understand how fluctuations in body weight might relate
to personality changes, psychological scientist Angelina Sutin of the Florida
State University College of Medicine and colleagues at the National Institutes
of Health (NIH) examined data from two large-scale longitudinal studies of
“We know a great deal about how personality traits
contribute to weight gain,” said Sutin. “What we don’t know is whether
significant changes in weight are associated with changes in our core
personality traits. Weight can be such an emotional issue; we thought that
weight gain may lead to long-term changes in psychological functioning.”
How the study was
The studies, NIH’s Baltimore Longitudinal Study of Aging
(BLSA) and the Baltimore Epidemiologic Catchment Area (ECA) study, included
more than 1 900 people in total, of all ages and socioeconomic levels. Data
about participants’ personality traits and their body weight were collected at
two time points separated by nearly a decade.
In one study, a
clinician measured participants’ weight at the two time points; in the other
study, the participants reported their weight at baseline and had it measured
by a clinician at follow-up.
Sutin and colleagues found that participants who had at
least a 10% increase in body weight showed an increase in impulsiveness — with
a greater tendency to give in to temptations — compared to those whose weight
was stable. The data don’t reveal whether increased impulsiveness was a cause
or an effect of gaining weight, but they do suggest an intimate relationship
between a person’s physiology and his or her psychology.
In a surprising twist, people who gained weight also
reported an increase in deliberation, with a greater tendency to think through
their decisions. Deliberation tends to increase for everyone in adulthood, but
the increase was almost double for participants who gained weight compared to
those whose weight stayed the same.
“If mind and body are intertwined, then if one changes the
other should change too,” Sutin said. “That’s what our findings suggest.”
Negative feedback has
Sutin and colleagues speculate that this increase in
deliberation could be the result of negative feedback from family or friends —
people are likely to think twice about grabbing a second slice of cake if they
feel that everyone is watching them take it.
These findings suggest that even though people who gain
weight are more conscious of their decision-making, they may still have
difficulty resisting temptations.
“The inability to control cravings may reinforce a vicious
cycle that weakens the self-control muscle,” the researchers note. “Yielding to
temptation today may reduce the ability to resist cravings tomorrow. Thus,
individuals who gain weight may have increased risk for additional weight gain
through changes in their personality.”
Co-authors are National Institute on Aging researchers Paul
Costa, Wayne Chan, Yuri Milaneschi, Alan Zonderman, Luigi Ferrucci, and Antonio
Terracciano, also at Florida State University College of Medicine; and William
Eaton of Johns Hopkins Bloomberg School of Public Health.
The research was supported by the Intramural Research
Program of the National Institute on Aging and a grant from the National
Institute on Drug Abuse.