Monday—if you’re concerned about long lines at the salad shop, that is. Salad chains tend to sell about 10 percent more salads on Mondays than any other day of the week, according to this Bloomberg Businessweek article. One chain said that Monday sales tend to exceed Friday sales by 17 to 22 percent!

Although this is fascinating for those in the business of marketing greens, it also tells an interesting story about our health behavior: that willpower tends to fade as we approach the weekend, and we use Monday as a “clean slate” day to start healthy habits all over again. Other research bears this out: One study found that people consume about 37 more calories per meal on weekends than on weekdays, turning the weekend into a potential weight-loss landmine. See these creative ways to outsmart common diet traps here.

I’m going to keep these stats in mind next time I’m craving pizza for lunch on Thursday or Friday. While a splurge now and then is certainly fine, we’d all do better to treat most workdays as though we have a case of the Mondays.

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