Intermittent fasting: Not as hungry as you expected?

Intermittent fasting diets, such as the 5:2 Diet, have gained popularity with the public and received considerable media attention. Although the physiological outcomes of such diets are well researched, less is known about psychological and behavioural aspects of intermittent fasting. One possibility is that intermittent fasting diets are popular because they do not require constant caloric restriction and involve simple diet rules. However, a potential barrier to intermittent fasting is concern over uncontrollable hunger. In an online study, we explored whether intermittent fasters (n = 95) hold different beliefs about hunger and fasting than other dieters (n = 60) and non-dieters (n =1 45). All participants completed a questionnaire assessing their personal theories of hunger and eating. Intermittent fasters were asked about their experience of fasting, including positive and negative consequences. Other dieters and non-dieters were questioned about their expectations of what they would experience if they fasted intermittently. We observed significantly different scores across the three groups for personal theories of hunger and eating. Specifically, intermittent fasters demonstrated less attribution of hunger to the body's physical need for energy. More broadly, expectations about hunger and negative consequences of fasting expressed by other dieters and non-dieters were inconsistent with outcomes reported by the intermittent fasters. Together, these data suggest that perceived barriers to fasting may not match the reality experienced by those who regularly engage in intermittent fasting. Challenging unfounded negative expectations about intermittent fasting may encourage more people to adopt this successful approach to reducing energy intake.