An Italian scientist has revealed that too many calories - not too much fat - is the reason why certain meals upset the stomach. According to Dr. Roberto Penagini, from the University of Milan, people who suffer from gastroesophogeal reflux disease (GERD) are often warned against eating fatty food, which is thought to exacerbate heartburn symptoms. But low-fat diets, he argues, do not necessarily help people with GERD, a chronic condition in which acid from the stomach flows back into the esophagus, causing severe heartburn.