Long term maintenance of weight loss is generally poor, which is at least partly due to increased feelings of hunger associated with restricting what can be eaten. Intermittent severe energy restriction is a novel dietary strategy that requires individuals to consume a very-low energy diet for 1-4 days per week, allowing normal feeding patterns to be adopted on the other days in the week. However, the effect of a consuming a very-low energy diet on appetite regulation, which might represent a key marker of long-term adherence to dieting, has not been determined. This study aimed to assess the effects of severely restricting energy intake for 24 h on markers of appetite regulation, energy balance and metabolism compared to an adequate energy trial.