Diet Tip—Close Your Eyes

January 31, 2003 at 7:30 pm

How many times has your resolve to eat prudently been sabotaged by the sight of a buffet table, Mom’s Thanksgiving specialties, or pastries on the dessert cart?

Just because a plate is full of food doesn’t mean one has to finish it all. For many of us, new data show, listening to the way our bodies signal they’ve had enough may require taking our eyes off that plate for a meal or two.

There’s no question that the mere look of certain foods can seduce us into eating at least a bit more. Indeed, most food advertising is based on precisely that premise.

What many of us may not realize is that food’s eye appeal may subtly encourage overeating at each and every meal. It starts by encouraging us to put too much food on our plates. Then, if we aren’t lucky, we may subconsciously feel compelled (thanks to early behavioral conditioning by our parents) to finish each meal with a “clean plate.”

A team of Swedish researchers has investigated the impact of even an ordinary food’s visual appeal and shown that it’s enormous. How did the scientists discover this? They blindfolded study volunteers, all obese, who then chose to eat one-quarter less food–with no loss in satisfaction.

Don’t worry, says study leader Britta Barkeling of Huddinge (Sweden) University Hospital, “there is no book coming out called the Blindfold Diet.” However, she says, eating the occasional meal while blindfolded may prove useful in teaching behavior modification–helping us home in on previously ignored cues to satiety.

What you can’t see. . .

In their new study, Barkeling’s team invited 18 middle-age, overweight people to lunch–twice. Each time, the volunteers were served a big plate of food sitting on a table specially fitted with a computerized scale. This device quantified the amount of food removed with each forkful and even timed the interval between bites and the total time for the meal. Lunches were served at an individual’s normal mealtime. Before then, right after, and every 60 minutes for the next 3 hours, diners rated their hunger, satiety, and desire to eat.

The menu consisted solely of hash–diced meat mixed in with fried onions and potatoes, Barkeling explains, because “the meal had to be homogenous, with every bite containing the same mix of nutrients and calories.” Each person also received a large glass of water.

Barkeling and her colleagues invited the volunteers to eat until they were full. The only difference between the two lunches is that on one occasion the men and women could see what they were eating, and the other time they had to eat blindfolded.

On average, the participants took about 10 minutes to eat either meal, downing 470 grams of food when they could see it and 359 grams when they couldn’t–a difference of 24 percent. Nevertheless, in their survey responses throughout the afternoon, the diners felt as sated with these smaller portions as they had with the larger ones. Barkeling’s team reports its findings in Obesity Research.

Last year, the Swedish scientists published a similar study of normal-weight volunteers, that time comparing nine blind individuals with nine sighted ones. Blind diners ate the same amount of hash as the sighted participants did when they could see the hash. However, on the day the sighted volunteers ate their lunch blindfolded, their consumption dropped 22 percent–again, with no drop in their reports of feeling full that afternoon.

The earlier study suggests that blindfolded people would eventually adapt to not seeing their food and increase their intake. Therefore, Barkeling observes, the value of the blindfold may be just in making people aware that they typically eat more than they need to. Indeed, she says, many people who enter her obesity clinic “tell us that they can’t feel hunger or satiety.” It appears they’ve lost the ability to sense when it’s time to stop eating. Occasionally eating blindfolded, she says, forces them to look for cues other than merely emptying their plates.