A systematic review of the effects of experimental fasting on cognition

Abstract

Numerous investigations have been conducted on the impact of short-term fasting on cognition in healthy individuals. Some studies have suggested that fasting is associated with executive function deficits; however, findings have been inconsistent. The lack of consensus regarding the impact of short-term fasting in healthy controls has impeded investigation of the impact of starvation or malnutrition in clinical groups, such as anorexia nervosa (AN). One method of disentangling these effects is to examine acute episodes of starvation experimentally. The present review systematically investigated the impact of short-term fasting on cognition. Studies investigating attentional bias to food-related stimuli were excluded so as to focus on general cognition. Ten articles were included in the review. The combined results are equivocal: several studies report no observable differences as a result of fasting and others show specific deficits on tasks designed to test psychomotor speed, executive function, and mental rotation. This inconsistent profile of fasting in healthy individuals demonstrates the complexity of the role of short-term fasting in cognition; the variety of tasks used, composition of the sample, and type and duration of fasting across studies may also have contributed to the inconsistent profile. Additional focused studies on neuropsychological profiles of healthy individuals are warranted in order to better develop an understanding of the role of hunger in cognition.

Keywords: Cognition; Executive function; Fasting; Hunger; Memory; Psychomotor speed.