May 29, 2000 -- Overweight people who substituted the diet shake Slim Fast for one or two meals a day for five years were able to lose weight and keep it off, a study in the journal Nutrition reports.
"I'm particularly excited about this study because it's a real-world study, in contrast to so many of our other studies which have been university-based," Harry Greene, MD, tells WebMD. "Participants in this study simply read information from the product's can and were provided with a small diet manual, and they did it on their own." Greene is medical director for Slim Fast Foods, which sponsored the study.
About 150 overweight men and women from communities in northern rural Wisconsin took part in the study. Each participant was matched with three other overweight community members of the same gender and approximately the same age, who were studied for comparison purposes. Study participants received Slim Fast shakes free of charge and were initially put on a three-month diet, where the shakes were substituted for one or two meals each day. Participants then used the shakes as a substitute for one meal a day or more if they saw their weight was starting to increase. Their weights, and those of the group not using Slim Fast, were recorded throughout the study.
"Those who used the shakes saw an average weight reduction of about 10 pounds. People who did not use the shakes gained an average of about 15 pounds, so that's a difference of 25 pounds," Greene says. "Just that fact that [the Slim Fast users] didn't gain weight is a success in itself.
"If we're going to do anything about the epidemic of obesity in this country, we're going to have to provide people with something they can use on their own, that's simple to implement, and that they can use long-term to help them learn how to eat better," Greene says. "We see Slim Fast as one part of our whole program, geared around current nutrition guidelines, to help people do that."
Barbara Rolls, PhD, professor of nutrition at Pennsylvania State University, in University Park, and author of Volumetrics: Feel Full on Fewer Calories, tells WebMD that she sees products like Slim Fast as a mixed blessing.
"Providing people with a portion-controlled dollop of nutritionally balanced calories not only helps them stick to a weight-loss plan, it also makes them more aware of what they're eating," she says. "My concern with studies like this is, it doesn't teach people how to deal with real food in real settings. Once the free supplement is taken away, how are they going to deal with going out to lunch, or a cocktail party? That's what people need to learn to manage their weight over the long run."
"I don't intend to demean Slim Fast, which is nutritionally balanced, but if we provided people with a portion-controlled hamburger containing a certain number of calories as a meal and they only consumed that, we'd see the same impact on weight.
"There's nothing magical about this particular product," she says. "It's simply one way of controlling intake."