 The idea behind intermittent fasting comes from the fact that rodents in caloric restriction experiments quickly ate all of the food they were given. That meant that they weren't just getting fewer calories, their eating pattern also changed to a single large meal followed by a long fast. So the improvements in these experiments might have been because of the reduction in calories or because of the unusual eating pattern. To find out, scientists did experiments to separate the effect of fasting from eating fewer calories. Broadly speaking, experiments with nematodes, fruit flies and rodents showed that many of the health and lifespan benefits of caloric restriction also happened on a fasting diet.