In a 2008 study, researchers linked drinking just one diet soda a day with metabolic syndrome — the collection of symptoms including belly fat that puts you at high risk of heart disease. Researchers aren't sure if it's an ingredient in diet soda or the drinkers' eating habits that caused the association.
Smarter sub: Flavored seltzer water. It has zero calories and is free of artificial sweeteners but provides fizz and flavor. Beware of clear sparkling beverages that look like seltzer yet contain artificial sweeteners — they're no better than diet soda. Or try a sparkling juice; we recommend watering it down with seltzer to stretch your calories even further.
Health bonus: Hydration (without chemicals). Water is essential for nearly every body process.
Try: Your supermarket's low-cost seltzer brand. The taste is the same as the bigger name brands.