June 25, 2001 WASHINGTON - Eating a limited variety at mealtime may be a good way to control weight, according to a new study that reviews the research on diet, food intake and repercussions to body composition. This study appearing in the current issue of Psychological Bulletin, published by the American Psychological Association (APA), demonstrates that being exposed to a variety of foods may not be the spice of life when trying to lose weight.
The variety in our diets keeps us from tiring of the taste of the food, explain authors Hollie A. Raynor, M.S., R.D., and Leonard H. Epstein, Ph.D., of the University of Buffalo. This decreases the feeling of satiation - feeling full - so humans and animals are more likely to overeat when they are in a situation where they can taste different foods. When given one food, sensory-specific satiety is more likely. This is a phenomenon that occurs when a food's palatability is lessened because the food is eaten until the person is satiated, which lessons the pleasantness of the taste of that particular food and foods that are similar, said the authors.
The modern day diet with all of its variety nullifies this phenomenon from happening. One benefit, said the authors, of having access to many different foods is that it can give a species an evolutionary advantage - eating a variety of foods offers different nutrients and may prevent nutritional deficiencies.
But those more vulnerable to obesity are not at an evolutionary advantage when exposed to a variety of foods, say the authors. They may show less sensory-specific satiety and therefore have a tendency to overeat because they are not tiring of the taste of the food. On the other hand, they may have greater sensitivity to sensory-specific satiety and be more motivated to consume multiple foods when given a large variety of foods so they won't tire of the food - the danger of meals presented buffet-style, said the authors.
From our review of 58 studies, we found that dietary variety could increase food consumption in both humans and animals, said Raynor and Epstein. "Both people and animals will eat more food when a meal or diet contains greater variety of food, which can eventually cause weight gain. So it isn't surprising that a typical American diet that consists of a large variety in foods like sweets and snacks is linked to being overweight."
In one study, participants were given four courses of food: sausages, bread and butter, chocolate dessert and bananas. Those who had different foods for each course consumed 44 percent more than those who ate the same food for each course. Another study had a similar finding. When different foods are available at the same time during a meal - tuna, roastbeef, cheese and egg sandwiches - overeating is more likely than compared to a meal of just one of these foods.
But, if the foods are similar, meaning that their sensory characteristics are alike, then increased eating is less likely, said the authors. For example, studies that offered participants flavors of yogurt similar in color and texture (cherry, raspberry and strawberry) showed no increases in eating. This result was also found in a study that used three different flavored chocolate candies that were similar in appearance and texture.
The results of this review suggest that a reduction in dietary variety of highly palatable, energy-dense foods may be useful in treating and preventing obesity, said the authors. "Limiting these foods in a meal may help reduce the energy intake within a meal, thereby reducing overall intake. Plus, the research shows us that meals composed of foods with similar sensory qualities (taste, shape and color), also may curb overeating during a meal."
Article: "Dietary Variety, Energy Regulation, and Obesity," Hollie A. Raynor, Ph.D., and Leonard H. Epstein, Ph.D., University of Buffalo; Psychological Bulletin, Vol 127, No. 3
Full text of the article is available from the APA Public Affairs Office or at http://www.apa.org/journals/bul/bul1273325.html
The American Psychological Association (APA), in Washington, DC, is the largest scientific and professional organization representing psychology in the United States and is the world's largest association of psychologists. APA's membership includes more than 155,000 researchers, educators, clinicians, consultants and students. Through its divisions in 53 subfields of psychology and affiliations with 60 state, territorial and Canadian provincial associations, APA works to advance psychology as a science, as a profession and as a means of promoting human welfare.
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