Yann Cornil and Pierre Chandon of the INSEAD Business School in Fontaineblue, France, analyzed two seasons of NFL games and people's food consumption.
On Mondays following a Sunday game in the National Football League, the researchers found that people in cities with a losing football team ate about 16 per cent more saturated fat and 10 per cent more total calories compared to their usual Monday consumption.
In contrast, people in cities with a winning football team ate about eight per cent less saturated fat and five per cent fewer total calories compared to their usual consumption.
Eating patterns stayed at usual levels in cities without an NFL team or with a team that didn't play.
"Overall, what this shows is that we're much less under control over eating as we'd like to believe," Chadon said in an interview.
"The environment, broadly speaking, so who wins, who loses, how food marketing is in place where you live, influences a lot of our food decisions without us being aware of it necessarily."
Chandon said he was surprised to find the effects were greater in cities where the defeats were narrow, which suggests it's disappointment that influences unhealthy eating.
These trends held even when people who weren’t football fans were included in the sample.
The researchers also tested the associations in a series of experiments. They asked French participants to write about a time when their favourite team lost or won while they were offered chips, candy, grapes or tomatoes. Those whose team won tended to snack on the healthier options while those in the losing group chose more junk.
The study, published in the journal Psychological Science, also pointed to a potential solution for fans of losing teams.
"Just thinking about the other things that are out there in life that matters to you influences how much people eat and completely eliminated the effect of the defeat."
The CBC's Kim Brunhuber caught up with fans of winning and losing NHL teams to find out whether their diet patterns changed after their favourite teams faced off.