Intermittent vs. Continuous Energy Restriction for Weight Loss and Metabolic Improvement

Just one lifestyle modification can go a long way: how do intermittent energy restriction (IER) and continuous energy restriction (CER) compare as weight loss strategies? 

Obesity has led to significant health risks throughout the years; this includes diabetes, cardiovascular disease, kidney disease, metabolic syndrome, cancer, and musculoskeletal disorders. However, with simple lifestyle modifications, losing weight can help decrease blood pressure, cholesterol, glucose levels, and other health–related issues.  

In a recent study, participants with overweight or obesity were compared by intermittent energy restriction (IER) or continuous energy restriction (CER) to see which has a more significant effect on weight loss. Intermittent energy restriction consisted of periods of a low energy diet of 500 to 600 kcal, alternating with periods of unrestricted food intake. A continuous energy restriction diet consisted of 500 to 750 kcal daily. Following the CER diet was very challenging for participants because of energy being limited daily.  

Before the study, participants received dietary education and were given electronic scales to measure their daily energy intake. The study was based on a 5:2 day diet; this meant there were two consecutive or non-consecutive fasting days and a total of 5 days in which to eat as much as necessary. The participants in IER had a total reduction of 400 to 600 kcal on fasting days compared to CER groups who had a 400 to 600 kcal reduction daily. 

There was a total of 11 randomized controlled trials. Using the meta-analysis, intermittent participants showed a higher effect of weight loss compared to continuous energy restriction. The study included a search for other articles that were previously published within ten years. The total weight loss in the study (WMD: −0.95 kg; 95% CI: −1.63 to −0.27; P=0.01) and the percentage of weight loss (WMD: −1%; 95% CI: −2 to 0; P= 0.02) were more significant for intermittent than for continuous. There was a decrease in fasting insulin with participants doing IER for sensitivity analysis. Overall, the data proved that the intermittent energy restriction diet works, and participants lost more weight than with continuous energy restriction. In the study, IER and CER reduced cardiovascular, blood pressure, lipids, and cancer mortality. A significant decrease in fasting insulin with intermittent energy restriction was shown in the sensitivity analysis.  

The study had some limitations that included too short of a study. The study was only done for a 2 to 3-week period. There was no comparison to healthy participants compared to participants who have well-controlled diabetes. There was also a small sample size along with other participants who dropped out of the study. The study did not mention what the diet consists of, what exactly went into the meal prep. For future studies, specific foods can be mentioned in the study, along with a time log. The study can be done for a longer time frame, instead of a 2 to 3 week period, it can be six months to a year. 

Practice Pearls: 

• Intermittent energy restriction is more effective than continuous energy restriction for patients who are at risk of overweight, obesity, and other health risks. 
• Patients lost about 5% more weight by an intermittent energy restriction diet compared to the continuous energy restriction. 
• Patients who have controlled diabetes can try intermittent fasting with a proper medication regimen and adequate blood glucose monitoring. 

Harris L; Hamilton S; “Intermittent Fasting Interventions for Treatment of Overweight and Obesity in Adults: a Systematic Review and Meta-Analysis.“  

He, Shasha, et al. “Intermittent Versus Continuous Energy Restriction for Weight Loss and Metabolic Improvement: 21 Dec. 2020, onlinelibrary.wiley.com/doi/full/10.1002/oby.23023?af=R. 

JB, Carter S, Clifton. “Effect of Intermittent Compared With Continuous Energy Restricted Diet on Glycemic Control in Patients With Type 2 Diabetes:  

Obesity. “Intermittent vs. Continuous Energy Restriction for Weight Loss and Metabolic Improvement.” January 4, 2021 

Anina Pham, PharmD. Candidate, Lake Erie College of Osteopathic Medicine, College of Pharmacy