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You burn the midnight oil

Sure, you need to log time at the gym, but to lose weight, you also need to log time in your bed.

Skimping on sleep, especially sleeping less than five or six hours a night, can slow your metabolism and cause hormonal changes that hurt your weight-loss efforts.

Being tired may also make you eat more. One recent study found that people who are sleep-deprived consume a whopping 500 extra calories a day.

Next: You exercise too much