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 Minnosota,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 regimen,four of the six people lost weight. Even the ramaining 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