CHAPEL HILL - So-called "thigh-reducing" creams, marketed to overweight women and normal-weight women who believe their thighs are too large have no positive physical effect beyond moisturizing.
That's the conclusion researchers drew after measuring the thighs of volunteers who applied the creams for six weeks in the first well-controlled scientific study of the products.
The study, presented Thursday (June 3) at the American College of Sports Medicine's annual conference in Seattle, showed no significant difference between upper-leg circumference when women rubbed the creams on one thigh every day and a lotion not touted as fat-reducing on the other.
"Manufacturers of these creams rake in the bucks for a product that doesn't work," said Dr. Bonita Marks, assistant professor of physical education, exercise and sport science at the University of North Carolina at Chapel Hill. "They feed on unfounded, poor self-images many women have of their bodies."
Others involved in the research were Drs. Jerome Haky of Florida Atlantic University and Laurence Katz, assistant professor of emergency medicine at the UNC-CH School of Medicine.
Because of the time required to process each volunteer daily, researchers concentrated on only 11 women, all students at UNC-CH or Florida Atlantic University. The women, who ranged in age from 18 to 35, applied "thigh-reducing" cream to one leg for six weeks and an inactive product to the other. They were asked not to change their routines by dieting or exercising more during the study than before. Neither scientists nor subjects knew which leg got what until the end of the project.
"I was amazed at the types of women responding to participate," Marks said. "They were not the ones we would think might need it, but rather they were mostly young, normal-weight women."
Researchers used special equipment to measure each volunteer's thighs near the knee, at mid-thigh and near the hip at the beginning and end of the six weeks. They also had the women fill out questionnaires about their perceptions.
"Not only did we find no difference in each volunteer's thighs at the end, but the volunteers themselves said they could see and feel no difference either," Marks said. "They said both products worked well as moisturizers, and surprisingly, they seemed to be less negative about their thighs at the end of the study. We don't know why."
The supposed active ingredient in "thigh-reducing" creams is aminophylline, a bronchorelaxant used to treat asthma, she said. In the laboratory, it was found to dissolve some fat cells, and so manufacturers began putting it in creams. They assumed it might have a similar effect on what some people have called "cellulite," or dimpled fat on the body, and an earlier study supported that notion.
But during the previous research, the women, who were obese, also dieted and exercised. Marks and colleagues repeated those experiments without the diet and exercise and added psychological assessments. One of their findings, published separately in February in the International Journal of Obesity, was that aminophylline did not enter the blood stream and thus had no positive or negative effects on the heart or lungs. In other words, it may not work, but at least it won't hurt when used moderately.
"It's interesting the way the cosmetics industry gets around FDA regulations for marketing the creams and how close they come to fraudulent advertising without actually breaking any advertising claim rules," Marks said. "This stuff can cost as much as $30 a bottle, while the average moisturizing cream costs about $3."
In their advertising and packaging, the industry uses glowing testimonials from "satisfied" customers and says the creams work better if one also diets and exercises.
A foundation grant from Florida Atlantic University to Marks and a Petroleum Research Fund grant administered by the American Chemical Society to Haky paid for the study.
Other research on aminophylline and its potential to reduce fat by increasing metabolism showed it was not effective enough in humans to continue studying, Marks said.
The above story is based on materials provided by University Of North Carolina At Chapel Hill. Note: Materials may be edited for content and length.
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