The 80% Rule

http://health.msn.com/fitness/womens-fitness/articlepage.aspx?cp-documentid=100254483>1=31050

"Most guys avoid anything that even smacks of perfectionism," and that applies to dieting, too, says Prevention adviser Pamela Peeke, M.D., an assistant clinical professor of medicine at the University of Maryland School of Medicine. "When women start a diet, they go from zero to 100—they become 'perfect' overnight, which is a hallmark of failure.
That's why I developed the 80 percent rule: Hit your weight-loss goals 80 percent every single day you can. One day, it'll be 120 percent because it happens to be a great day. Other days, you'll hit 50 percent or even 20 percent when you're dealing with PMS. Just make sure it averages out to 80 percent."