Conventional dietary interventions are based on the idea that a calorie is a calorie, regardless of the time of day it is ingested. However, accumulating evidence suggests that the timing of food intake might predict weight loss effectiveness. Energy homeostasis has been linked to circadian rhythm at a physiological and behavioural level, but the way calories are used and the impact of energy expenditure on weight-related hormones throughout the day is not well defined. Eating at the ‘ideal’ time of day might help to improve metabolic health and body weight maintenance.

Chrono-nutrition is an emerging field of nutrition that aims to understand the effects of meal timing on health. Evidence suggests that calorie consumption in the morning is associated with higher energy expenditure in relation to energy intake, suggesting that preferentially eating in the morning could support weight loss.