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

Abstract

BackgroundIntermittent 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.ObjectivesTo 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).MethodsForty-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.ResultsOf 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).ConclusionBoth 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.

Intermittent fasting and health outcomes: an umbrella review of systematic reviews and meta-analyses of randomised controlled trials

“… 16 IF (TWF, MADF, ADF, and IER) for 1–12 months was associated with increased HDL-C in adults with overweight or obesity, and T2DM compared with CER (MD = 0.03 mmol/L; 95% CI, 0.01–0.05; p = 0.010). 36 Two non-significant effects with high quality evidence were observed for 4–12 weeks IF (ADF, TRE, TWF, and ADF plus CR) or 8–52 weeks IF (MADF, TRE, and TWF) than CER or no treatment for TC. 14 , 16 However, limit the fasting mode to ADF, TC was decreased (SMD = −0.29; 95% CI: −0.48 to −0.10; p = 0.003) compared with a non-intervention diet.…”

“…The final selection yielded 23 meta-analyses to be included for the main analysis. 12 , 13 , 14 , 15 , 16 , 17 , 18 , 19 , 20 , 31 , 32 , 33 , 34 , 35 , 36 , 37 , 38 , 50 , 52 , 53 , 61 , 62 , 63

Fig. 1 Flow diagram of the study selection process .

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“… 16 Five associations conducted on participants with overweight or obesity, T2DM patients, metabolic syndrome, and premenopausal women, compared IF (MADF, ADF, TRE, IER, TWF, and ADF plus CR) with CER diets or non-intervention diet, reporting no significant effects with high quality evidence on fasting glucose (n = 4) and fasting insulin (n = 1). 14 , 16 , 36 Three significant associations conducted on participants with overweight or obesity, T2DM patients, and metabolic syndrome, compared IF (MADF, ADF, TRE, and TWF) with CER diets or non-intervention diet, reporting moderate (n = 1) and low (n = 2) evidence on HOMA-IR. 16 , 38 , 62 Ten associations conducted on participants with obesity or overweight, T2DM and at least 1 risk marker for metabolic syndrome, premenopausal women, compared IF (TWF, MADF, and TRE) with usual diet, ad libitum, unrestricted, or CER diets, reporting no significant effects on HbA1c (three moderate, six low, and one very low).…”

“… 14 IF (TWF, ADF, IER, and MADF) for 4–48 weeks increased HDL-C in individuals with overweight or obesity, and T2DM compared with CER diet. 36 …”

“… 4 It is essential for us to summarize and provide an updated overview of the evidence, considering the volume of these meta-analyses. 31 , 32 , 33 , 34 , 35 , 36 , 37 , 38 When a limited number of studies are included or when there is considerable heterogeneity among the results, it becomes challenging to elucidate the source of heterogeneity through subgroup analysis. Consequently, such limitations can reduce the level of evidence obtained.…”