Differences in fairness and trust between lean and corpulent men

Employment disparities are known to exist between lean and corpulent people, for example, corpulent people are less likely to be hired and get lower wages. The reasons for these disparities between weight groups are not completely understood. We hypothesize (i) that economic decision making differs between lean and corpulent subjects, (ii) that these differences are influenced by peoples' blood glucose concentrations and (iii) by the body weight of their opponents.

A total of 20 lean and 20 corpulent men were examined, who performed a large set of economic games (ultimatum game, trust game and risk game) under euglycemic and hypoglycemic conditions induced by the glucose clamp technique.

In the ultimatum game, lean men made less fair decisions and offered 16% less money than corpulent men during euglycemia (P=0.042). During hypoglycemia, study participants of both weight groups accepted smaller amounts of money than during euglycemia (P=0.031), indicating that a lack of energy makes subjects to behave more like a Homo Economicus. In the trust game, lean men allocated twice as much money to lean than to corpulent trustees during hypoglycemia (P<0.001). Risk-seeking behavior did not differ between lean and corpulent men.

Our data show that economic decision making is affected by both, the body weight of the participants and the body weight of their opponents, and that blood glucose concentrations should be taken into consideration when analyzing economic decision making. When relating these results to the working environment, the weight bias in economic decision making may be also relevant for employment disparities.