Reality Check
Don't expect that midslope energy drink to help you stay lean. Contrary to what you might infer from their labels, new "calorie-burning" drinks like Celsius and Coca-Cola's green-tea-based Enviga (available in January) are not designed for weight loss, according to company officials. It takes three cans of Enviga (at five calories each) to rev up your metabolism enough to burn 60 calories—hardly a liquid road to Slimville. Think of it as a green-tea Diet Coke with more caffeine than a cup of coffee.

C Ration
New research suggests that a lack of vitamin C decreases the efficiency with which you oxidize—that is, burn—fat during exercise. One-third of Americans have below-adequate concentrations of vitamin C, according to Carol Johnston, a professor of nutrition at Arizona State University, who coreleased the findings.

The Carnivore's Dilemma
Turns out the Atkins diet won't, as some critics suggested, kill you. A 20-year study at Harvard found that the proportion of protein to carbs in a diet had no effect on heart health. However, subjects who got their protein from tofu and beans rather than meat dropped their heart-disease risk by 30 percent. The study also found that diets based on foods with a high glycemic index (like white bread and potatoes) doubled heart-attack risk even in low-fat diets. Our advice: Wrap your black beans in a whole-wheat tortilla.