Effects of Intermittent Fasting on Performance in U.S. Military Personnel While Operating OCONUS – A Review

Linderman JK, O’Hara RB. Effects of Intermittent Fasting on Performance in U.S. Military Personnel While Operating OCONUS – A Review. JEPonline 2020;23(3):1-12. Fitness of highly trained military and special operations forces (SOF) exceeds that of the general population. In individuals with such levels of fitness, fasting decreases physical performance. The 30-day-period of Ramadan requires the observant to abstain from food or fluid from sunrise to sunset, ranging from 11 to 18 hrs a day. Ramadan Intermittent Fast (RIF) results in decreased lean body mass (LBM), muscle strength, and endurance. Hypohydration increases resting heart rate (HR) and decreases resting blood pressure, while sleep alterations may impair psychomotor task performance. Collectively, these changes appear to be more profound in fit individuals. The primary purpose of this review is to summarize and contrast research on RIF and fasting on human performance. The secondary purpose examines performance relevant to operational forces operating outside the continental U.S. (OCONUS). The Areas of focus include muscular strength, cardiovascular function and endurance, and neuromuscular function. A literature search ranging from 1975 to 2015 used PubMed identified 35 relevant sources. The data indicate that RIF results in a caloric deficit, reduction in sleep, and hypohydration that are associated with a decrease in LBM, strength, endurance capacity, and psychomotor function. Policies that require the observation of the RIF practices raise the potential for concern of personnel safety and mission success.