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Negative calories? That's the boast of one new drink promising enhanced calorie burning in a tasty beverage. The other magic word on new diet products is satiety, which means the item will (supposedly) make you feel satisfied sooner and keep you feeling full longer, so you'll eat less. Calorie burners and satiety enhancers are so hot, they're two of the top 10 food and beverage trends for 2007, says marketing research firm Datamonitor.
The Calorie Burners
• On the shelves: Enviga (Coca-Cola and Nestle's new green tea sparkling beverage), Celsius, Fuze Healthy Infusions Slenderize, Jana Skinny Water, JavaFit Diet Plus Gourmet Coffee.
• Claims: "The great taste of burning calories!" "Lose weight — gain energy" are a couple of the slogans you'll see in advertisements or on labels. Some of the products also promise to curb appetite, boost your metabolism, and burn fat.
• Evidence: The key ingredient in many of these beverages is green tea extract, caffeine, or, often, a combination of the two. Short-term studies have shown that these ingredients can give your metabolism a small boost (by about 3.5 percent in one study of the combo) and burn an average of 78 calories. But researchers writing in a 2006 issue of Obesity Reviews say that additional studies are needed to determine whether the products actually help you lose over a long period. What's more, metabolism changes in a controlled experiment don't necessarily translate to weight loss in the real world.
Some products include ingredients that you often find in over-the-counter weight-loss supplements, including Citrus aurantium, chromium picolinate, or Garcinia cambogia. Reviewing the value of these ingredients in a recent article in Obesity Management, George Bray, M.D., of the Pennington Biomedical Research Center, concluded there was little to no evidence that they make it easier to drop pounds.
• Shopping advice: These products are calorie free (or virtually so). If you have a sugary-soda habit, switching to any diet drink can help you lose. Just don't count on the "calorie-burning" additives in these new drinks to make a huge difference: Even the Coca-Cola Company's own research showed that drinking three cans of Enviga a day burned, on average, only an extra 60 to 100 calories, which can be wiped out if you swipe just a forkful of your husband's dessert. (Still, 100 calories a day could add up over time, if you keep your fork to yourself.)
• Watch out for: Citrus aurantium (sometimes listed as bitter orange or Seville orange) if you have high blood pressure or other cardiovascular problems. It can raise blood pressure and also interact with medications used to treat these disorders, say researchers from Georgetown University Medical Center. Combining Citrus aurantium with caffeine may magnify the risks.
Satiety Builders
• On the shelves: Dannon Light & Fit Crave Control yogurt; Lightfull Satiety Smoothie; Quaker Weight Control instant oatmeal; Slim-Fast Optima shakes; Special K20 Protein water, snack, and meal-replacement bars.
• Claims: Helps satisfy hunger, "surprisingly filling," controls hunger longer.
• Evidence: All these foods contain added protein and/or fiber. Research has shown that eating more protein can quell hunger and cut food intake. In a study at the University of Washington School of Medicine, a group of subjects doubled the amount of protein in their diet and spontaneously ate about 441 fewer calories a day, losing, on average, almost 11 pounds in 12 weeks. And numerous studies over the last two decades have linked diets high in fiber with lower body weights. But in these studies, people's eating habits were completely transformed. Just adding a bit of fiber and protein to your yogurt "isn't going to help you lose weight," cautions Barbara Rolls, Ph.D., a satiety expert and nutrition professor at Penn State University. Slim-Fast Optima shakes work in a different way: These meal-replacement drinks have been reformulated so that fat digestion is delayed, which stimulates the release of hormones that send fullness signals to your brain. Early studies suggest that this new technology does work.
• Shopping advice: As snacks, these fiber- and protein-enriched products are clearly better choices than cookies or chips. And if you find meal-replacement products useful, Slim-Fast Optima shakes may help get around the "hungry again in an hour" problem.
• Watch out for: Exaggerated promises. Ordinary fruits, vegetables, whole grains, and lean meats probably control hunger just as well.
