“Lose 20 pounds in three weeks.” “Drop weight while you sleep.” And now, add a “Slim Down Booster” to your smoothie to give your mind and body a boost.

Weight loss advertisements are everywhere. Promises of rapid weight loss with minimal effort entice buyers desperate to change their bodies.

Freshens, a national franchise specializing in smoothies and frozen yogurt, has over 1,500 locations in the United States, including 23 on college campuses.

One nutritional “booster” is included in the cost of a drink. Patrons can choose between the Immune, Energy, Femme Support, Protein, Multivitamin and Slim Down.

Slim Down Boosters are the most popular according to cashier Karla Campos, who described serving around 60 Slim Down Boosters during one eight-hour shift.

While Freshens sells the booster, it is manufactured by the company MET-Rx Engineered Nutrition, and contains the following four ingredients: l-tyrosine, taurine, l-carnitine and caffeine.

The theory behind putting caffeine in dietary supplements is to raise both the heart rate and core body temperature in order to increase the metabolic rate to burn fat and cause weight loss.

“It’s called thermogenics,” said Byron Bell, the manager of the Courthouse Plaza General Nutrition Center in Arlington, which sells similar products.
Caffeine also inhibits sleep, and the longer a person stays awake, the more calories he or she burn.

“But when you spend that extra time awake snacking, it cancels out the extra calories burned,” said Dr. Mark Kantor, associate professor in the Department of Nutrition and Food Science at the University of Maryland.
Student Health Center Dietitian Jane Jakubczak performed a study on supplement boosters like the one provided at Freshens and found that the amounts given were so minimal, that even if they did what they were advertised to do, “the serving was too small for an effect.”

As for the other ingredients, Bell, Kantor and Jakubczak agreed that they have nothing to do with weight loss.

L-carnitine has not been found to increase metabolic rates, but it is thought to relieve soreness in tired muscles after a long work out.

L-tyrosine has also never been linked to weight loss, but it is tied to depression relief in some studies.

Taurine is a common ingredient in many energy drinks, but no connection has been found between it and muscle growth. It is, however, essential for cat health.

“Sometimes companies just put these different ingredients in because other companies are doing it,” Kantor said.

He found this to be true in a study he performed on popular energy drinks, where unrelated ingredients are included because consumers see them on one label, assume they are important, and thus only buy those drinks that carry the same unrelated ingredients.

Janice Caulfield, a customer service representative for Freshens, explained that the ingredients in the Slim Down Booster are amino acids and that taurine is found in energy drinks that you buy over the counter. However, she did not know how the booster works in terms of weight loss.

Linda Cook, an information representative for MET-Rx, also did not know how the ingredients cause weight loss.

The Freshens and MET-Rx Web sites display footnotes at the bottom of the page saying that the Food and Drug Administration has not evaluated the statements about the booster.

The Federal Trade Commission has posted a brochure on its Web site helping consumers spot the “red flag” advertisements from the factual ones.