In a recent observational study, researchers found that in a large group of Korean men and women, sleep quality had a strong effect on diet quality and risk of obesity in women, but not in men.
 
Short sleep duration, and poor overall sleep quality, has long been implicated as a possible risk factor for metabolic issues including obesity, as well as poor diet quality. Research has proposed a number of potential reasons for this link – poor sleep often results in reduced physical activity, changes in appetite, satiety, and energy balance which could alter food intake, and responses to hormones such as leptin and ghrelin, which affect appetite and metabolism.
 
In the present study, researchers tracked results of 737 men and 428 women in Korea who participated in the prospective Ewha-Boramae cohort study – all participants had undergone full health assessments, including anthropometric measures and sleep quality indices.
 
In the study population, 43.6% of men and 17.5% of women were categorized as obese, and no significant differences between men and women’s physical activity levels were observed. For men, those most at risk of developing obesity were married adults and current smokers. Women most likely to be obese tended to be older, and in post-menopause.
 
Obese women, compared to non-obese women, had significantly lower sleep quality indicators and lower diet quality. In sum, women with poor sleep quality were approximately twice as likely to be obese compared to women who had a Pittsburgh Sleep Quality Index score of 5 or greater. However, improvements in diet quality, as measured by the Recommended Food Score, reduced the risk of developing obesity in women with poor sleep quality.
 
Men in the present study were unaffected by poor sleep quality, at least when it came to a heightened obesity risk. “The source of this disparity is unclear, but it could be explained by gender-based differences in leptin and other metabolic hormones implicated in the sleep-wake cycle and food intake behavior in women […] sex/stress hormones, obesity, and aging all influence sleep duration/quality, either independently or in combination.”
 
While this study suggests that interventions in diet quality might act as a modifier for obesity risk in women with poor sleep quality, further studies with larger sample sizes in an prospective or interventional design are needed, the authors of the study concluded.