The Cheater’s Diet is a book and plan by Paul Rivas, MD.  He prescribes a healthy Mediterranean Diet on weekdays, splurging (not binging) on weekends, and regular aerobic exercise all the time. He claims that eating more on weekends boosts the metabolic rate, but that has not proven. Your friend’s interpretation, calling for less than 1000 calories a day, is unnecessarily severe, as well as unhealthy, and places her at risk of binging during the weekend indulgence.  Ultimately, the approach is unnecessary because data from the Weight Control Registry shows that successful losers always eat moderately and indulge in treats on a case-by-case basis.