Optimal sleep: a key element in maintaining a healthy body weight

Abstract As obesity rates rise globally, addressing modifiable lifestyle factors, such as sleep, presents an opportunity for public health interventions. This review explores the growing evidence linking sleep duration, quality, and timing with weight management and dietary behaviours throughout the life course. Observational studies associate short or irregular sleep with increased obesity risk, poor diet quality, and metabolic disturbances. Plausible mechanisms include decreased physical activity, heightened hedonic and/or emotional eating, dysregulated appetite signals, and circadian misalignment of metabolism, which contribute to a positive energy balance. Unravelling the bidirectional relationship between sleep and weight is challenging; poor sleep exacerbates weight gain, while obesity-related comorbidities such as obstructive sleep apnoea further impair sleep. Despite promising evidence from sleep restriction studies showing increased energy intake, long-term randomised controlled trials (RCTs) examining interventions designed to improve sleep with weight management as an outcome are lacking. A handful of short-term interventions suggest benefits in reducing energy intake or improving dietary quality, but their effects on weight loss remain inconclusive. This review calls for robust, well-powered RCTs that integrate sleep, diet, and physical activity interventions to evaluate the potential of sleep as a core component of obesity prevention and treatment strategies. Currently, there is insufficient evidence to support sleep-focused interventions as a mandatory element in clinical weight management programmes.