Adding pureed vegetables to entrees reduces the number of calories the meals pack without sacrificing texture or taste, according to Pennsylvania State University researchers who tried it on unsuspecting adult study subjects.
Using "stealth vegetables" to pad dishes provided a double-helping of dietary benefit, the University Park group reports, because some of the participants more than doubled their intake of fibre- and vitamin-packed veggies - without even knowing it.
The study included 20 men and 21 women who agreed to eat at a laboratory once a week for 3 weeks. The meals were always the same: carrot bread for breakfast, macaroni and cheese for lunch and chicken-and-rice casserole for dinner. Volunteers were served as much as they wanted to eat, along with side dishes like bread rolls, strawberry yogurt, broccoli and green beans, depending on the meal. They also were given snacks to take home for the evening, such as carrot sticks and fig cookies.
Portion sizes were strictly controlled by weight and the researchers kept a close account of the amount of food participants ate. The study was published online February 2 in the American Journal of Clinical Nutrition.
Unknown to the diners, back in the kitchen, cooks were adding vegetables that had been steamed then pureed -- cauliflower, squash or carrots, depending on the entrée - to some of the main dishes. The result was a helping of food that, although it looked, tasted and otherwise resembled the original, was either 15% or 25% vegetable puree by weight. Some participants got the traditional version of the entrees with no hidden veggies.
The imposter ingredients didn't seem to faze the study subjects, who all ate about the same amount of a given entree regardless of how much puree, if any, it contained. As a result, the researchers say, the subjects' calorie intake dropped substantially when they were consuming the altered foods - by as much as 360 calories a day when the entrees consisted of 25% puree. Meanwhile, the subjects' vegetable intake rose by up to two servings a day, a substantial improvement over the typical American diet.
By cutting back 360 calories every day, a person could lose one pound of body fat in about 10 days.
Although nearly half the participants said at the end of the study that they could tell something was different about the altered meals, only two said they could taste the extra vegetables.
Dr. Richard Mattes, professor of foods and nutrition at Purdue University in West Lafayette, Indiana, said promoting consumption of fruits and vegetables is "highly desirable", but added that they are far from a panacea for weight loss.
Dr. Mattes, who wasn't involved in the Penn State research, found in another study that even people who lose weight on a diet high in fruits and vegetables said they wouldn't stick to the meal plan. "Many people said they were not going to spend the extra money on fresh fruits and vegetables, or shop more often, or spend more time preparing them," he said.
For the moment, Dr. Mattes added, Americans don't seem eager to embrace healthy diets. The very premise of the latest study - covert feeding to encourage better eating - underscores the resistance. "It's interesting that we have to go to such extents to get people to consume" more vegetables, he said.
The latest government diet guidelines recommend limiting portion sizes and filling half of one's plate with fruits and vegetables rather than meat or carbohydrates. - (Reuters Health, March 2011)
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