A Systematic Review of the Literature on Intermittent Fasting for Weight Management

Daily calorie restriction is the most common weight loss approach. However, intermittent calorie restriction or fasting (ICR) is an approach promoted widely in the media, though not new, but an established ritual of many religions. Studies which examined the use of ICR for weight management were sought. Three databases were searched: Science Direct, PubMed and Cochrane Library between 1975 to 2014. Inclusion criteria comprised; human studies, cyclic/periodic calorie restriction, duration >2 weeks, randomised trial design initial reported body weight or BMI >22kg/m2 and weight change. The review identified 7 studies which used ICR strategies for both weight loss and maintenance, of which 6 were considered for analysis due to a duplication of data reporting. All studies included overweight or obese participants and were heterogeneous in duration and sample size. Three studies focused on weight loss while 3 others focused on both weight loss and weight maintenance. Weekly fasting periods differed, 3 studies used 2 ICR days per week, 1 used 4 days, another used 1 day and 3 used a mixture of 2 and 5 fasting days weekly. Six studies reported mean weight loss of 2.6% after first month, 5.8% after 2 months, 6.4% after 3 months and 8.9% after 6 months of weight loss and further mean weight loss of 8.2% after a month of weight maintenance. The impact of ICR interventions on blood pressure and insulin sensitivity was recorded. All studies reported a decrease in blood pressure up to 4% and 4 reported decreased insulin concentrations with 3 reaching the reference range. Attrition rates were lower than seen in many studies of weight management, at around 20%. Current research evidence to estimate the impact of ICR is limited. Findings are indicative, sample sizes small and further research justified.