A new battle is developing in the long-running cola wars — with the new weapon being low-carb colas. Pepsi Edge hit Iowa stores last week while Coca-Cola’s C-2 is expected on shelves this week. Wendy Macke, a registered dietician at the Iowa Heart Center, says people who are watching their carbohydrates — and watching their weight — probably shouldn’t be drinking colas anyway.They’re still a source of sugar and calories containing carbs and Macke says colas are “not exactly healthy choices.” She says people who are trying to live healthier lives while dropping a few pounds need to follow a more sensible diet and develop an exercise routine.Macke recommends drinking lots of water, not pop, and eating fruits, vegetables and whole-grain breads and pastas, while watching portion sizes. She says dueling news releases from Coke and Pepsi look, at first glance, like the new low-carb drinks could have some benefits — but then she analyzed them more closely.The two drinks tout low-carb statistics but for serving sizes of only eight ounces — and the beverages are only being sold in 20-ounce bottles, meaning, most people will drink more than twice the serving size. Macke says water’s cheap, carb-free and much better for you. She recommends eight eight-ounce servings of water every day.