The latest diet trend in America is also an ancient human activity. The activity is fasting, or not eating food for a set amount of time. Social media apps and Facebook groups are appearing for people who do “intermittent fasting,” or fasting on a part-time basis. Like other diets, intermittent fasting helps you lose weight by setting limits on eating. But instead of limiting what you eat, it limits when you eat. One of the more popular approaches to intermittent fasting is called “time-restricted feeding.” It is not as difficult as some of the other approaches, since the fasting period can include the time you are sleeping. The basic idea of time-restricted feeding is to limit eating to an eight-hour period. You then fast during the day’s other 16 hours. Many people make the eating period shorter or longer. Some eat just one meal a day.