A new animal study suggests that adding vinegar to a typical high-fat diet may help prevent weight gain. Researchers fed one group of mice a fatty diet along with acetic acid--a component of vinegar--for six weeks. Another group of mice were fed the same fatty diet but had water instead of vinegar. At the end of the study both groups had gained weight, but the mice fed vinegar gained 10 percent less than their water-fed peers. Experts say they're not sure if eating vinegar will prevent weight...