Big decisions are best made on a full stomach, research suggests.
Skipping meals lowers levels of a brain chemical key in keeping careless and impulsive behaviour in check.
As a result, our hearts may overrule our heads - leading to bad decisions being made.
Cambridge University scientists made the link between the chemical serotonin and decision making after looking at how a group of men and women reacted to being treated unfairly.
The 20 volunteers took part in a game in which one offers the other a share of some money.
If the offer is accepted, both players are paid their split. If rejected, neither player gets anything.
Normally, a sense of resentment at being treated unfairly leads to players rejecting up to a third of low offers - despite it meaning they will leave empty-handed.
It seems the heady feeling produced by denying the unfair player any cash more than makes up for the loss of payment.
But when serotonin levels were low - something that occurs when we haven't eaten - the number of low offers turned down rose to more than 80 per cent, the journal Science reports.
In other words, lack of serotonin increased the likelihood of the player making an unfair offer effectively being told where he could put his money.