Created by the Director of the Vanderbilt University Weight Management program, PhD Martin Katahn's (T-Factor Diet) simple theory has been around since 1986. The Rotation Diet - which has different approaches for men and women - promises weight loss of a pound a day via a process of varying caloric intakes over a three week period, then repeating the cycle. Women use the caloric numbers of 600, 900 and 1200 calories, and men use the caloric numbers of 1200, 1500 and 1800 calories. For the first three days, a Rotation dieter eats 600 or 1200 calories a day. For the next four days the allotment is the 900 or 1500 calories a day. Then - for an entire week - you're allowed to indulge in the1200 or 1800 calories a day. Then, you repeat the first seven days's cycle. At this point you are given a reprieve to return to your normal eating habits, then you begin the Rotation all over again.
So there are a number of ideas at work in the Rotation Diet: first, this is extremely low calorie, so much so that weight loss is essentially guaranteed. Second, the mixing up of the calorie counts and the days is a seeming attempt to prevent boredom, as well as catering to the theory that you can manipulate your metabolism by not allowing your body to get used to a specific number of calories. Katahn does note that most extreme low calorie diets (read: starvation) actually slow your metabolism because your body is in fact going into starvation mode to protect itself - and his instructions to mix it up are intended to counteract that process.
Katahn provides recipes, and recommends and provides guidance permanent lifestyle change elements like regular exercise, drinking plenty of water and avoiding junk food. Like all extremely low calorie diets, the Rotation will undoubtedly lead to weight loss. How could it not, on 600 calories a day? But can you live this way? The Rotation Diet can be useful for kickstarting weight loss, but is not a long-term, lifestyle solution for healthy weight maintenance.