The study revealed that people who do their shopping when being hungry are more likely to buy fattening or highly caloric foods: specifically, up to 45% more high-calorie foods.

The study was conducted with two groups of paid volunteers. One group of 34 volunteers was kept hungry for five hours, while the other group of 34 people was given food and instructed to eat until sated.

Then, the 68 volunteers were asked to go shopping in an online simulated grocery store, where there was a mix of low-calorie and high-calorie food. The hungry volunteers bought more high-calorie foods, even if the overall amount of food they bought wasn’t different from the sated volunteers.

In a second study, the researchers focused on the time of day when people shop, based on an earlier study that divided the shopping day in two: when people were more likely to be full (between 1 pm and 4 pm), and when people were more likely to be hungry (4 pm to 7 pm).

People shopping at ‘higher hunger hours’ bought less low-calorie food compared with people shopping at the ‘lower-hunger, after-lunch hours’ period.

Endocrinologist Tony Goldstone from London Imperial College told Reuters Health that the findings are based on the authors' assumptions of when people would be hungrier, so they should be interpreted cautiosly.

Goldstone further explains that it's an instinct to search for more caloric food after a fasting period, and it stems from an evolutionary time when humans had no certain supply of food.

According to the Arizona State University, shopping when hungry can make your bill go up by 17%.