Husbands and wives are more likely to quarrel if they are "hangry" - hungry and angry, say scientists.
Experts believe low levels of blood sugar may be linked to marital arguments, confrontations and even domestic violence.
The antidote is to eat a carbohydrate snack or something sugary, suggesting that cake or chocolate might help to placate an angry spouse.
"People can relate to this idea that when they get hungry, they get cranky," said US lead researcher Dr Brad Bushman, from Ohio State University.
"We found that being 'hangry' can affect our behaviour in a bad way, even in our most intimate relationships."
Dr Bushman's team conducted a study with 107 married couples that involved participants sticking pins into voodoo dolls representing their spouses.
Each husband and wife was allocated a doll and, acting alone, told to stick up to 51 pins in it at the end of each day, depending on how angry their spouse had made them.
At the same time, participants used a blood glucose meter to test their blood sugar every morning and evening. The experiment was repeated for 21 days.
The results showed that lower blood glucose in the evening coincided with more pins being stuck in voodoo dolls.
Wives tended to stick more pins in their dolls than husbands.
"When they had lower blood glucose, they felt angrier and took it out on the dolls representing their spouse," said Dr Bushman.
"Even those who reported they had good relationships with their spouses were more likely to express anger if their blood glucose levels were lower."