Eat Dessert First? Your Willpower Signals Certain Personality Traits

Deciding whether or not to eat dessert may not just say something about how much you weigh but also says something about your thought process.

According to Florida State University College of Medicine and colleagues at the National Institute of Health, fluctuations in body weight may particularly relate to personality changes after they examined data from two large-scale longitudinal studies of Baltimore residents.

"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."

Statistics from NIH's Baltimore Longitudinal Study of Aging (BLSA) and the Baltimore Epidemiologic Catchment Area (ECA) study looked at 1,900 people from all ages and socioeconomic backgrounds.

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 percent 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."

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.