Dieters may start examining their choice of friends in addition to their choice of food, according to a recent study co-authored by Dartmouth economics professor David Blanchflower. The study revealed that perceptions about weight and weight's effect on happiness are linked to a person's body mass index, a measure of weight scaled by height, relative to that of his or her peers.
"We wanted to examine to what extent people care about their weight and how that was affected by their peer group," Blanchflower said.
Blanchflower said his team sought to determine if residents of countries in which the average body mass index is rising are less concerned about their personal weight gain. The team studied populations in which the average body mass index has risen during the past 10 years.
The team analyzed data from more than 27,000 male and female respondents of varying ages from 29 European countries. The researchers divided subjects into peer groups of the same age, gender and country of origin.
Overweight people were more likely to report negative feelings about their weight if their body mass index was higher than their peer group's average. If two overweight people with the same body mass index had different peer groups, the overweight person from the peer group with a higher average body mass index was more likely to underestimate his or her degree of obesity and also to report fewer feelings of unhappiness related to being overweight, Blanchflower explained. Women were more likely than men to feel overweight, regardless of their actual body mass index, he said.
The researchers conducted the study as part of a larger effort to analyze factors that contribute to personal happiness, Blanchflower said, adding that the team's research focused on physical characteristics that people can easily compare among their peer groups, such as height or weight.
The researchers are currently studying the impact of high blood pressure on happiness. They also plan to evaluate the effects of height and substantial weight loss due to dieting on emotional well-being.
"Overall, we're interested in attitudes and particularly what drives these attitudes to change," Blanchflower said.
The team presented the study on July 25 at the National Bureau for Economic Research's Summer Institute, an academic conference. Andrew Oswald, economics professor at the University of Warick, England, and Bert Van Landeghem, economics professor at the University of Leuven, England, co-authored the study.
