The prevalence of overweight and obesity in US adults is currently 68%, compared with about 47% in the early 1970s. Many dietary factors have been proposed to contribute to the US obesity epidemic, including the percentage of energy intake from fat, carbohydrate and protein; glycemic index; fruit and vegetable intake; caloric beverage intake; and fast food or other restaurant food intake. One factor that may also be important is the variety of foods in the diet having different sensory properties, that is, flavors, textures, shapes and colors. A host of studies show that when presented with a greater variety of foods within a meal, humans consume about 22% more energy compared to when only one food is available. These data are supported by laboratory animal studies on the effects of sensory variety on consumption as well as body weight and fat gain. Longer term experimental trials in humans lasting 1-2wk had mixed results but generally showed an increase in intake of 50-60kcal/d per additional food offered, provided at least 5 different foods per day were available. In only two studies to date has reducing dietary variety been explored as a potential method for weight loss. In those studies, which also incorporated a standard behavioral weight loss approach, there was no difference in weight loss when either snack food variety or low nutrient dense, high energy dense variety was limited. However, a broader treatment approach may be more effective, for example limiting the excess variety of foods high in energy density yet which provide little benefit to vitamin and mineral intake at each meal, and further studies are needed in this area.
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