There are many reasons to avoid junk food. The main reason we think of, is to lose weight. However, junk food is also bad for our digestive system. Since most junk food has a lot of fat, and fat can weaken the lower esophageal sphincter muscle, many people get heartburn symptoms or GERD with these snacks. Similarly, fatty foods can stimulate the Gallbladder to contract, and may cause gallbladder symptoms in people with gallstones. For an interesting podcast by Deborah Kotz of US News and World report, go to How You Eat Can Make a Big Difference in Your Health.