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Aug. 11, 2000 -- New research puts a positive spin on being 'full of hot air'. The study, published in the August issue of the American Journal of Clinical Nutrition, shows that feeling full can be a great weapon in the battle of the bulge. The researchers suggest that food portions that seem bigger can reduce hunger and cut down on calories -- even if the bigger portions are just puffed up with more air.
"The perception of taking in a large volume of food can trick people into thinking they're eating more calories," researcher Barbara J. Rolls, PhD, tells WebMD. She is chairwoman and professor of nutrition at Pennsylvania State University.
In Rolls' study, 28 young, lean men were offered as much food as they wanted from a buffet for breakfast, lunch, and dinner, one day weekly for four consecutive weeks. On three of the four test days, they were given a milk shake 30 minutes before lunch. The milk shakes were all made with the same amount of the same ingredients, so that they all had the same calorie count and nutritional value, but were whipped up with different amounts of air to change their size.
The smallest shake was a little less than the size of a soda can, the largest was twice that size, and the third milk shake was in between. The shakes were served in a clear glass with a straw, so that the men would be aware of the portion size.
After drinking the largest shake, men ate 12% less at lunch than they did after drinking the smallest shake, and they also reported less hunger, more sensations of fullness, and decreased amount of food that they felt like eating. Even better, they did not eat more at dinner to compensate for eating less at lunch.
Sounds good -- but don't rush out to the ice cream parlor for a milk shake before lunch, at least not if you want to lose weight. The men in the study still consumed more calories overall -- because of the shake -- even though they ate less.
Rolls says she believes that the increased volume of the milk shake made subjects feel less hungry by fooling the brain into thinking more was eaten, by stretching the stomach to make it feel full, and by increasing stimulation of the mouth and throat during eating.
"Think big," says Rolls, offering advice on how to increase volume of food eaten while cutting down on calories. She suggests flaked or puffed cereals that look like a larger portion instead of cereals that pack down into a smaller volume, low fat frozen desserts, and blender drinks. Popcorn -- without the melted butter, of course, is high in volume, and weighs in at only 90 calories for three cups.
"Adding high-volume, low-calorie foods before meals may be useful if the person has control over eating behaviors and understands what constitutes a 'normal' full feeling," nutritionist Sally Myers, RD, CPT, at Fair Oaks Medical Plaza in Fairfax, Va., tells WebMD. She was not involved in the study.
Myers cautions that these results should be taken with a grain of salt. "Over 50% of our patients eat for emotional reasons, psychological reasons, or because they love food and eating." She says that before surgery, drinking large amounts of water before meals did not decrease food consumption in most of her patients.
Rolls' research did not involve obese men and women, and only looked at eating behavior in the short term. However, based on her other studies, Rolls says she believes that findings would be similar in these groups, even in long-term studies.
Earlier work by Rolls suggests that adding water to food may be another good way to fool ourselves into feeling less hungry. In her book Volumetrics: Feel Full on Fewer Calories, she explains that food with higher water content can help you lose weight by feeling more satisfied. For example, it would take almost three cups of strawberries -- loaded with water and other nutrients -- to equal the 100 calories found in only 10 jelly beans.