German researchers in the Psychological Assessment and Health Psychology department of the University of Konstanz may have discovered a new weight-loss device: a blindfold. While any promise of weight loss due solely to vision loss is probably a stretch, the researchers did find that people eat significantly less and are less interested in what they are eating when they are blindfolded and cannot see their food.
In this study, published in the June 2016 issue of the professional journal Food Quality and Preference, ninety university students, some blindfolded and others not, participated in what they thought was a taste test of ice cream. While both blindfolded and non-blindfolded students gave the ice cream positive ratings overall, blindfolded participants rated the ice cream lower in flavor, freshness and refreshing quality, and found it less pleasant to eat. Those who were blindfolded also overestimated how much they ate, but actually ate 9% less ice cream than those who were not blindfolded.
Our reaction to food is purely sensual, and sight is the sense that helps us choose the foods we will eat. When you look at food, the researchers point out, you get a “visual flavor” that colors your perception of the food, your willingness to buy the food, and how much of it you eat.
The researchers aren’t sure why the blindfolded students overestimated the amount of food they actually ate, or whey they rated it less pleasurable and ate less than the non-blindfolded students. Normally, your brain communicates with your digestive tract to regulate how hungry or full you feel at different stages of a meal, and the sight of food contributes to this communication. The researchers theorize that the results of this study could be due to the disruption in this communication caused by blindfolding. Another theory is that visual deprivation causes other senses to become more acute so, for instance, the sense of smell is sharpened, which would affect both appetite and taste. Since the students could not use sight to monitor their food, it is also possible they overestimated how much they ate because they knew they were eating something they perceived to be unhealthy.
Several past studies found that when people are blindfolded, they not only eat significantly less food, they feel just as satisfied after a meal as when they eat without a blindfold. In other words, without visual cues, smaller portions were just as filling as larger portions.
If blindfold eating isn’t your thing, but you’re looking for ways to help yourself eat less food, it might help to turn down the lights. Although one earlier study found that people who ate in a darkened restaurant actually consumed 6% more than when the restaurant was lit, researchers think this was due more to the amount of food they were given than to the lack of visuals: In the dark, the diners ate almost everything on their plates. Serving size matters—had they been given smaller portions, the diners may have been just as satisfied as their blindfolded counterparts.
The real take-away here is that since we are visually stimulated by food to the degree that we may eat more when we like what we see, it might make sense to routinely make less exciting choices when you’re making an effort to lose weight or struggling to maintain a healthy weight. Save ice cream and other fun-but-calorie-dense foods for special occasions!
Renner B, Sproesser G, Stok FM, Schupp H. Eating in the dark: A dissociation between perceived and actual food consumption. Food Quality and Preference. June 2016; 50:145-151