The Comparison of the Effects between Continuous and Intermittent Energy Restriction in Short-Term Bodyweight Loss for Sedentary Population: A Randomized, Double-Blind, Controlled Trial

Effects of intermittent dieting with break periods on body composition and metabolic adaptation: a systematic review and meta-analysis

CONTEXT

Intermittent dieting incorporated with break periods (INT-B) has recently been promoted as an alternative dietary approach for optimal weight management.

OBJECTIVE

This study assessed the effectiveness of INT-B compared with that of conventional continuous energy restriction (CER) for improving body composition and attenuating metabolic adaptation.

DATA SOURCES

A systematic search was conducted on 6 databases using all available records until July 2023.

DATA EXTRACTION

The extracted data included the lead author, year of publication, population characteristics, intervention protocols, duration, and adherence.

DATA ANALYSIS

Random-effects meta-analyses were conducted for within-group and between-group comparisons of anthropometric and metabolic outcomes. Subgroup moderator analysis was performed for the types of INT-B, intervention duration, and population characteristics.

RESULTS

Of the 1469 records, 12 randomized trials (with 881 participants) were included. Within-group analyses demonstrated significant improvements in body mass, fat mass, body mass index, body fat percentage, and waist circumference following both INT-B and CER, with no significant group differences. However, resting metabolic rate (RMR) was significantly reduced following CER only. The compensatory reduction in RMR was significantly smaller following INT-B compared with CER, suggesting a lesser degree of metabolic adaptation. INT-B had a more significant effect on RMR retention in individuals with overweight/obesity compared with resistance-trained individuals.

CONCLUSION

This review provides up-to-date evidence for INT-B as a viable dietary strategy to improve body composition and attenuate metabolic adaptation.

SYSTEMATIC REVIEW REGISTRATION

PROSPERO registration no. CRD42023448959.

Differential effects of intermittent energy restriction vs. continuous energy restriction combined high-intensity interval training on overweight/obese adults: A randomized controlled trial

BACKGROUND

Intermittent energy restriction (IER) and continuous energy restriction (CER) are increasingly popular dietary approaches used for weight loss and overall health. These energy restriction protocols combined with exercise on weight loss and other health outcomes could achieve additional effects in a short-term intervention.

OBJECTIVES

To evaluate the effects of a 4-week IER or CER program on weight, blood lipids, and CRF in overweight/obese adults when combined with high-intensity interval training (HIIT).

METHODS

Forty-eight overweight/obese adults [age: 21.3 ± 2.24 years, body mass index (BMI): 25.86 ± 2.64 kg⋅m-2] were randomly assigned to iER, cER, and normal diet (ND) groups (n = 16 per group), each consisting of a 4-week intervention. All of the groups completed HIIT intervention (3 min at 80% of V̇O2max followed by 3 min at 50% of V̇O2max ), 30 min/training sessions, five sessions per week. iER subjects consumed 30% of energy needs on 2 non-consecutive days/week, and 100% of energy needs on another 5 days; cER subjects consumed 70% of energy needs; and ND subjects consumed 100% of energy needs. Body composition, waist circumference (WC) and hip circumference (HC), triglyceride (TG), total cholesterol (TC), low-density lipoprotein-cholesterol (LDL-c), high-density lipoprotein-cholesterol (HDL-c), and cardiorespiratory fitness (CRF) were measured before and after the intervention.

RESULTS

Of the total 57 participants who underwent randomization, 48 (84.2%) completed the 4-week intervention. After intervention body composition and body circumference decreased in three groups, but no significant differences between groups. The iER tends to be superior to cER in the reduction of body composition and body circumference. The mean body weight loss was 4.57 kg (95% confidence interval [CI], 4.1-5.0, p < 0.001) in iER and 2.46 kg (95% CI, 4.1-5.0, p < 0.001) in iER. The analyses of BMI, BF%, WC, and HC were consistent with the primary outcome results. In addition, TG, TC, HDL-c, and CRF improved after intervention but without significant changes (p > 0.05).

CONCLUSION

Both IER and CER could be effective in weight loss and increased CRF when combined with HIIT. However, iER showed greater benefits for body weight, BF%, WC, and HC compared with cER.