Effects of Intermittent Energy Restriction Compared with Those of Continuous Energy Restriction on Body Composition and Cardiometabolic Risk Markers - A Systematic Review and Meta-Analysis of Randomized Controlled Trials in Adults.
Study Goal
The researchers aimed to compare the effects of different intermittent energy restriction (IER) diets (TRE, ADF, 5:2) with continuous energy restriction (CER) on anthropometrics and cardiometabolic risk markers in healthy adults.
Results Summary
Combined IER diets did not show superior improvements in anthropometrics or cardiometabolic markers compared to CER, though slight reductions in fat-free mass and waist circumference were observed. TRE reduced body weight and fat mass more than CER, while ADF improved insulin resistance more, and the 5:2 diet showed less BMI reduction than CER.
Population
Healthy adults
Effective Dosage
Not specified (protocols included time-restricted eating, alternate-day fasting, and the 5:2 diet)
Duration
2-52 weeks
Interactions
None mentioned
| Intervention | Direction | Endpoint | Population | Dosage | Impact | Claim # |
|---|---|---|---|---|---|---|
intermittent energy restriction (IER) diets combined | no change | body weight | healthy adults | WMD: -0.42 kg; 95% CI: -0.96 to 0.13; P = 0.132 | were comparable | #1 |
intermittent energy restriction (IER) diets combined | no change | fat mass (FM) | healthy adults | WMD: -0.31 kg; 95% CI: -0.98 to 0.36; P = 0.362 | were comparable | #2 |
intermittent energy restriction (IER) diets combined | decrease | fat-free mass | healthy adults | WMD: -0.20 kg; 95% CI: -0.39 to -0.01; P = 0.044 | reduced | #3 |
intermittent energy restriction (IER) diets combined | decrease | waist circumference | healthy adults | WMD: -0.91 cm; 95% CI: -1.76 to -0.06; P = 0.036 | reduced | #4 |
intermittent energy restriction (IER) diets combined | no change | body mass index [BMI (kg/m2)] | healthy adults | - | did not differ | #5 |
intermittent energy restriction (IER) diets combined | no change | glucose | healthy adults | - | did not differ | #6 |
intermittent energy restriction (IER) diets combined | no change | insulin | healthy adults | - | did not differ | #7 |
intermittent energy restriction (IER) diets combined | no change | homeostatic model assessment for insulin resistance (HOMA-IR) | healthy adults | - | did not differ | #8 |
intermittent energy restriction (IER) diets combined | no change | serum lipid and lipoprotein concentrations | healthy adults | - | did not differ | #9 |
intermittent energy restriction (IER) diets combined | no change | blood pressure | healthy adults | - | did not differ | #10 |
time-restricted eating (TRE) | decrease | body weight | healthy adults | - | reduced | #11 |
time-restricted eating (TRE) | decrease | fat mass (FM) | healthy adults | - | reduced | #12 |
time-restricted eating (TRE) | decrease | fat-free mass | healthy adults | - | reduced | #13 |
alternate-day fasting (ADF) | decrease | homeostatic model assessment for insulin resistance (HOMA-IR) | healthy adults | - | improved | #14 |
5:2 diet | decrease | body mass index [BMI (kg/m2)] | healthy adults | - | reduced less | #15 |
The interest in intermittent energy restriction (IER) diets as a weight-loss approach is increasing. Different IER protocols exist, including time-restricted eating (TRE), alternate-day fasting (ADF), and the 5:2 diet. This meta-analysis compared the effects of these IER diets with continuous energy restriction (CER) on anthropometrics and cardiometabolic risk markers in healthy adults. Twenty-eight trials were identified that studied TRE (k = 7), ADF (k = 10), or the 5:2 diet (k = 11) for 2-52 wk. Energy intakes between intervention groups within a study were comparable (17 trials), lower in IER (5 trials), or not reported (6 trials). Weighted mean differences (WMDs) were calculated using fixed- or random-effects models. Changes in body weight [WMD: -0.42 kg; 95% confidence interval (CI): -0.96 to 0.13; P = 0.132] and fat mass (FM) (WMD: -0.31 kg; 95% CI: -0.98 to 0.36; P = 0.362) were comparable when results of the 3 IER diets were combined and compared with those of CER. All IER diets combined reduced fat-free mass (WMD: -0.20 kg; 95% CI: -0.39 to -0.01; P = 0.044) and waist circumference (WMD: -0.91 cm; 95% CI: -1.76 to -0.06; P = 0.036) more than CER. Effects on body mass index [BMI (kg/m2)], glucose, insulin, homeostatic model assessment for insulin resistance (HOMA-IR), serum lipid and lipoprotein concentrations, and blood pressure did not differ. Further, TRE reduced body weight, FM, and fat-free mass more than CER, whereas ADF improved HOMA-IR more. BMI was reduced less in the 5:2 diet compared with CER. In conclusion, the 3 IER diets combined did not lead to superior improvements in anthropometrics and cardiometabolic risk markers compared with CER diets. Slightly greater reductions were, however, observed in fat-free mass and waist circumference. To what extent differences in energy intakes between groups within studies may have influenced these outcomes should be addressed in future studies.