Intermittent Vs Continuous Energy Restriction On Weight Loss And Metabolic Improvements:A Meta-Analysis And Systematic Review

Background and purpose:With the improvement of living standards,lifestyle changes and the aging of the population,the global overweight/obesity rate is increasing year by year.As a traditional weight management strategy,continuous energy restriction(CER)is difficult to adhere to for a long time.Intermittent energy restriction(IER)has gradually attracted people’s attention and interest in the past decades,mainly in the form of 5:2 diet and alternate-day fasting(ADF),but there is no consistent conclusion between them on weight loss and metabolic improvement.Purpose: to evaluate the effects of IER(5:2 diet/ADF)versus CER on weight loss and metabolic improvements in adults with overweight/obesity,and the adverse effects between them.Methods:Randomized controlled trials(RCTs)were systematically searched from PubMed,Embase and Cochrane Library for recent 10 years.Revman5.3 software was used for statistical analysis of the data.Effect sizes were expressed as weight mean differences(WMD)and 95% confidence intervals(CI).Results:A total of eleven randomized controlled trials(RCTs)were included(n = 850).Comparison of 5:2 diet and CER was in eight RCTs(n = 707),and ADF vs CER in three RCTs(n=143).Two RCTs(n =186)included people with diabetes.Intervention duration was from 2 to 12 months.Short term(2-3 month)intervention performed in5 RCTs and 6 RCTs in long term(6-12 month).The statistical differences in meta-analysis are as follows:1.Meta analysis showed that weight loss was greater for IER than CER: WMD:-0.95 kg;95% CI(-1.63,-0.27);P= 0.006;2.Meta analysis showed a significant reduction in fasting insulin with IER:WMD:-1.14 μU/ml,95% CI(-1.81,-0.47);P=0.0008;3.Meta analysis showed a significant reduction in HOMA-IR with IER: WMD:-0.22,95% CI(-0.4,-0.04);P=0.02;4.Subgroup analysis by duration showed a significant reduction in weight loss,FM(fat mass)and FFM(fat free mass)during short-term IER(P<0.05);Subgroup analysis by diet type showed ADF was associated with weight loss(P<0.05);5.There was no significant difference in other outcomes between groups.Conclusion:This systematic review showed that short-term weight loss was greater for IER(5:2 diet and ADF)than CER,and IER has comparative metabolic improvements and anti-inflammation with CER.Although more adverse effects were reported by IER,no serious events were reported,and with the time,most patients could tolerate it.Therefore,IER as an alternative diet therapy for weight loss is safe and feasible,and can provide patients with more options for weight loss.Further,longer and rigorous RCTs are needed to validate these findings.