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Dining under bright lights linked to healthier food choices

“We feel more alert in brighter rooms and therefore tend to make more healthful, forward-thinking decisions,” said Dipayan Biswas, one of the study’s authors.

Professor Dipayan Biswas' study showed people in the dimly lit rooms ordered 39 percent more calories.
REUTERS/Marcelo del Pozo

When people dine in dimly lit environments they are more likely to make unhealthy food choices than when they eat in a brighter venue, according to a new study published in the Journal of Marketing Research.

The study also found that this effect most likely results from the level of the diners’ mental alertness.

“We feel more alert in brighter rooms and therefore tend to make more healthful, forward-thinking decisions,” said Dipayan Biswas, one of the study’s authors and a professor of marketing at the University of South Florida, in a released statement

This finding is not going to make much of a difference in most people’s overall efforts to eat nutritiously and maintain a healthy weight (unless you dine out in restaurants frequently). But it does speak to a bigger issue: People make healthier food-related decisions when they are alert and mindful of what they’re doing.

Experiment No. 1

The new study was actually a series of five experiments. For the first one, Biswas and his colleagues observed the food choices made by 160 diners, aged 21 to 70-plus, at four casual chain restaurant locations (40 diners at each location). The researchers manipulated the lighting in the restaurants to make it dim (25 lux) at two of the locations and bright (250 lux) at the others. To avoid as many additional variables as possible, the researchers chose restaurants located near each other in the same major city, and they conducted the study at all four locations on the same evening.

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In addition to collecting information about the food choices made by the diners, the researchers also asked them to rate their alertness level on a 1 to 7 scale.

When all this data was analyzed, Biswas and his colleagues found that the diners in the brightly lit venues were 16 percent to 24 percent more likely to make healthier food choices than those in the dimly lit rooms. Specifically, people dining under bright lights were more likely to choose grilled or baked fish, chicken and vegetables and less likely to opt for fried foods and desserts. 

In fact, the people in the dimly lit rooms ordered 39 percent more calories. 

Data from the questionnaires also revealed that the diners’ mental alertness tended to be significantly higher in the brightly lit environments.

The follow-up experiments

In a series of follow-up laboratory experiments involving groups of university students, Biswas and his colleagues replicated these results. The in-lab experiments included narrower food choices, but more objective measurements of mental alertness.

In two of these experiments, the researchers gave diners a caffeine placebo (a drink the diners were told contained caffeine, but which didn’t). The purpose of the caffeine placebo was to prompt the diners to be more alert when selecting what to eat. (Other research has shown that people report similar alertness after drinking a caffeinated drink and a caffeine placebo.) And it did have an effect: When given the placebo, diners in dimly lit rooms were just as likely as those in brightly lit ones to make more healthful food choices.

These findings suggest that the main reason we make better food choices in brighter environments is that we feel more alert and, therefore, pay more attention to the nutritious qualities of the food.


The researchers emphasize that in their experiments ambient lighting led to relative higher or lower levels of unhealthy foods choices. In other words, plenty of people in the brightly lit settings selected higher-calorie meals.

In fact, in the first experiment’s brightly lit restaurants, only 52 percent of the diners made healthy meal choices.

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Still, that was a higher proportion than the 35 percent who did so in the dimly lit venues.

Nor is lighting the only factor that affects food choices. Other research has shown that people tend to eat more slowly and less food in dimly lit restaurants.

“Dim lighting isn’t all bad,” said co-author Brian Wansink, director of the Food and Brand Lab at Cornell University in New York (and authors of “Slim by Deign: Mindless Eating Solutions for Everyday Life”), in a released statement. “Despite ordering less-healthy foods, you actually end up eating slower, eating less and enjoying the food more.”

Just keep alert when you’re handed the menu in a dimly lit restaurant, he added. As in all food-related situations, it will help you refrain from overindulging.

FMI: You’ll find an abstract of the study on the website of the Journal of Marketing Research, but the full study is behind a paywall.