Keeping regular sleeping hours might be the easiest way for women to stay slim. A study from Brigham Young University found that young women who went to bed and woke up at the same time every day had lower body fat than women in the study who maintained irregular sleeping patterns. Sleeping between eight and 8.5 hours was associated with the lowest body fat among the study participants, comprised of 330 college women. Women whose sleeping patterns varied more than 90 minutes had higher body fat than those whose sleep patterns varied less the 60 minutes, the study found. It also showed that sleeping less than 6.5 hours or more than 8.5 hours was associated with higher body fat. The researchers theorized that the lower body fat seen among the regular sleepers might be a result of exercise, and noted that they only tracked the women’s sleep patterns for a week. Because this was simply an observational study, it doesn’t prove that regular sleeping patterns, on their own, affect amounts of body fat.
Bruce W. Bailey et al, “Objectively Measured Sleep Patterns in Young Adult Women and the Relationship to Adiposity, ” American Journal of Health Promotion doi: http://dx.doi.org/10.4278/ajhp.121012-QUAN-500