When is a 2,000-calorie meal fattening? It depends on what time you eat it. Dr. Franz Halberg, a professor of laboratory medicine and pathology at the universe of Minesota, probed this mystery in a study conducted a few years ago. Each day for a week, he fed six volunteers a single meal, eaten at breakfast time, which consisted of 2,000 calories. Then he gave the same participants the identical 2,000-calorie meal as dinner for a week. But on the dinner regiment, four of the six people lost weight. Even the remaining two lost more on the breakfast diet than on the dinner diet. Dr.Halberg's conclusion is that a calorie is not the same at breakfast as it is at dinner.