Table 1.

Characteristics of the included studies

Author (year) [ref]	Study design	Participants	Trial duration	N	Study groups	Age (years)	Males (n)	BMI (kg/m2) Waist-c (cm)	FM FFM (kg)	SBP DBP (mmHg)	Fasting glucose (mg/dL) Hb1Ac (%)	Fasting insulin (µU/mL) HOMA-IR (mmol/L * µU/mL)	Total chol (mg/dL)	HDL-c (mg/dL)	LDL-c (mg/dL)	TG (mg/dL)
Antoni (2018) [22]	RCT 2 parallel arms	BMI > 25 kg/m2 Age 18–65 years No comorbidity	8–10 weeks	15a	IER (2 days/week) = 25% of the energy need on 2 consecutive fast days and energy according to needs on feed days	42 ± 4	7	30 ± 1	31 ± 2	123 ± 3	79 ± 2	11 ± 1	162 ± 12	42 ± 4	100 ± 12	97 ± 9
								102 ± 3	58 ± 3	74 ± 3	ND	1.6 ± 0.2
				12a	CER: 600 kcal less than estimated needs	48 ± 3	6	31 ± 1	34 ± 3	115 ± 3	79 ± 4	9 ± 1	162 ± 12	39 ± 4	104 ± 8	80 ± 9
								102 ± 2	56 ± 3	75 ± 3	ND	1.3 ± 0.1
Carter (2016) [24]	RCT 2 parallel arms	T2DM BMI ≥ 27 kg/m2 Age ≥ 18 years No comorbidity	12 weeks	31	IER (2 days/week) = 400–600 kcal/day on fast days and no restriction on feed days	61 ± 8	16	35 ± 5	38 ± 9	134 ± 17	ND	ND	ND	ND	ND	ND
								ND	55 ± 11	84 ± 10	7 ± 1
				32	CER = 1200–1500 kcal/day every day	62 ± 9	14	36 ± 5	40 ± 11	138 ± 15	ND	ND	ND	ND	ND	ND
								ND	54 ± 9	90 ± 11	8 ± 1
Catenacci (2016) [27]	RCT 2 parallel arms	BMI ≥ 30 kg/m2 Age 18–55 years Non-smokers No diabetes, CV diseases, major comorbidity	8 weeks	15	IER (3 days/week) = 0 kcal/day on fast days alternate and energy according to needs, but with the chance to ask for more food, on feed days	40 ± 10	3	36 ± 4	38 ± 8	ND	88 ± 7	13 ± 6	170 ± 33	38 ± 8	100 ± 31	143 ± 56
								ND	53 ± 9		ND	ND
				14	CER = 400 kcal less than needs	43 ± 8	3	40 ± 6	49 ± 10	ND	92 ± 8	19 ± 6	171 ± 36	39 ± 7	104 ± 29	140 ± 43
								ND	61 ± 12		ND	ND
Conley (2018) [23]	RCT 2 parallel arms	Men with BMI ≥ 30 kg/m2 Age 55–75 years No diabetes No high alcohol intake or major comorbidity	24 weeks	12	IER (2 days/week) = 600 kcal/day on 2 non-consecutive fast days and energy ad libitum on feed days	68 ± 3	12	33 ± 2	ND	142 ± 14	108 ± 27	ND	151 ± 35	45 ± 12	77 ± 31	168 ± 53
								114 ± 5		84 ± 10	ND
				12	CER = 500 kcal less than needs	67 ± 4	12	36 ± 4	ND	150 ± 18	110 ± 31	ND	166 ± 39	46 ± 12	98 ± 35	212 ± 150
								123 ± 10		88 ± 14	ND
Coutinho (2017) [28]	RCT 2 parallel arms	BMI = 30–40 kg/m2 Age 18–65 years Inactive, no menopause or major comorbidity	12 weeks	18	IER (3 days/week) = 550–660 kcal/day on fast days and energy according to needs on feed days	39 ± 11	4	36 ± 3	47 ± 8	ND	ND	ND	ND	ND	ND	ND
								ND	60 ± 12
				17	CER = 33% of energy restriction every day	39 ± 9	2	35 ± 4	43 ± 8	ND	ND	ND	ND	ND	ND	ND
								ND	55 ± 9
Harvie (2011) [26]	RCT 2 parallel arms	BMI = 24–40 kg/m2 Premenopausal women Age 30–45 years Non-smokers, not using OC, no major comorbidity	24 weeks	53	IER (2 days/week) = 25% of the energy need on 2 consecutive fast days and energy according to needs on feed days	40 ± 4	0	31 ± 5	34 (31–36)	115 (111–119)	87 (85–88)	7 (6–8)	197 (189–197)	58 (54–58)	119 (112–127)	106 (88–124)
								102 (98–105)	48 (46–49)	77 (74–79)	ND	1.5 (1.3–1.8)
				54	CER = 25% energy restriction every day	40 ± 4	0	31 ± 5	35 (32–39)	117 (113–120)	87 (83–88)	7 (6–9)	200 (193–208)	62 (54–66)	119 (108–127)	115 (97–124)
								102 (99–106)	49 (48–50)	75 (72–78)	ND	1.6 (1.3–1.8)
Harvie (2013) [20]	RCT 3 parallel arms	Women with BMI = 24–45 kg/m2 or body fat > 30% of BW Age 30–45 years No major comorbidity	12 weeks	37	IER (2 days/week) = 25% of the energy need on 2 consecutive fast days and energy according to needs on feed days	46 ± 8	0	30 ± 4	31 (28–34)	115 (111–125)	88 (85–90)	6 (5–8)	204 (191–229)	50 (49–59)	128 (116–139)	088 (75–102)
								101 (97–104)	48.5 (46–50)	ND	5	1.6 (1.3–1.9)
				38	IER as above plus unlimited proteins and fats (non-SFA) on fast days	49 ± 7	0	31 ± 6	34 (30–37)	130 (115–138)	90 (86–92)	7 (6–9)	221 (206–237)	55 (51–59)	144 (130–159)	95 (81–109)
								104 (99–109)	49 (47–51)	ND	6	1.9 (1.5–2.2)
				40	CER = daily 25% restriction every day	48 ± 8	0	32 ± 6	36 (32–39)	124 (116–131)	90 (86–92)	7 (6–9)	205 (193–218)	51 (48–55)	129 (118–139)	97 (83–111)
								106 (102–110)	50 (48–52)	ND	6	1.8 (1.5–2.2)
Sundfor (2018) [21]	RCT 2 parallel arms	BMI = 30–45 kg/m2 Age 21–70 years Waist ≥ 84/90 cm (male/female) plus another component of the metabolic syndrome No comorbidity or alcohol/drug abuse	24 weeks	54	IER (2 days/week) = 400–600 kcal/day on 2 non-consecutive fast days and energy as usual on feed days	50 ± 10	28	35 ± 4	ND	129 ± 13	104 ± 22	ND	192 ± 35	47 ± 13	126 ± 32	162 ± 73
								116 ± 10		88 ± 8	6 ± 1
				58	CER = 400–600 kcal less than needs	48 ± 12	28	35 ± 4	ND	128 ± 13	103 ± 13	ND	197 ± 34	45 ± 10	133 ± 32	137 ± 60
								116 ± 10		86 ± 9	6 ± 1
Trepanowski (2017) [17]	RCT 3 parallel arms	BMI = 25.0–39.9 kg/m2 Age 18–65 years Non-smokers, inactive No menopause, diabetes, CV diseases	24 weeks	34	IER (alternate d/week) = 25% of the energy need on fast days and 125% of energy needs on feed days	44 ± 10	4	34 ± 4	38 ± 7	124 ± 12	90 ± 12	16 ± 14	188 ± 35	57 ± 14	111 ± 13	101 ± 59
								ND	55 ± 9	83 ± 9	ND	ND
				35	CER = daily 25% restriction every day	43 ± 12	6	35 ± 4	40 ± 7	122 ± 17	92 ± 18	20 ± 18	184 ± 35	53 ± 11	112 ± 31	97 ± 27
								ND	58 ± 12	80 ± 11	ND	ND
				31	C = no dietary intervention	44 ± 11	4	34 ± 4	36 ± 10	121 ± 16	87 ± 8	16 ± 9	190 ± 30	59 ± 13	112 ± 31	98 ± 43
								ND	53 ± 10	81 ± 11	ND	ND
Varady (2011) [19]	RCT 4 parallel arms	BMI = 25–39.9 kg/m2 Age 35–65 years Non-smokers, inactive No diabetes, CV diseases	12 weeks	15	IER (3 days/week) = 25% of the energy need on fast days and ad libitum on feed days	47 ± 2	3	32 ± 2 ND	ND	ND	ND	ND	ND	51 ± 3	141 ± 9	ND
				15	CER = 25% energy restriction every day	47 ± 3	2	32 ± 2 ND	ND	ND	ND	ND	ND	60 ± 6	137 ± 9	ND
				15	Moderate exercise program, no diet intervention	46 ± 3	2	33 ± 1 ND	ND	ND	ND	ND	ND	51 ± 4	122 ± 9	ND
				15	C = no dietary/exercise intervention	46 ± 3	2	32 ± 2 ND	ND	ND	ND	ND	ND	57 ± 3	136 ± 10	ND
Williams (1998) [25]	RCT, 3 parallel Arms	T2DM Age 30–70 years BW > 20% ideal Not currently on insulin, no liver, renal, heart diseases	20 weeks	18	IER (1 day/week) = 400–600 kcal/day on fast day and 1500–1800 kcal/day on feed days	51 ± 8	9	35 ± 5	ND	ND	177 ± 56	20 ± 11	215 ± 37	41 ± 8	132 ± 35	197 ± 83
								ND			8 ± 2	ND
				18	IER (5 days/week) = 400–600 kcal/day on fast day every 5 weeks and 1500–1800 kcal/day on feed days	50 ± 9	7	37 ± 5	ND	ND	182 ± 58	17 ± 7	208 ± 39	42 ± 7	131 ± 29	203 ± 239
								ND			8 ± 2	ND
				18	CER = 1500–1800 kcal/day every day	54 ± 7	7	35 ± 5	ND	ND	184 ± 61	22 ± 9	218 ± 42	46 ± 11	127 ± 48	167 ± 89
								ND			8 ± 2	ND

BMI body mass index, BW body weight, Chol cholesterol, CV cardiovascular, CER continuous energy restriction, DBP diastolic blood pressure, FFM fat free mass, FM fat mass, IER intermittent energy restriction, HDL-c high density lipoprotein-cholesterol, LDL-c low density lipoprotein-cholesterol, ND no data, OC oral contraceptives, RCT randomized controlled trial, SFA saturated fatty acids, SBP systolic blood pressure, TG triglycerides, T2DM type 2 diabetes mellitus, Waist-c waist circumference, Wk week

^aNot available the baseline data of all the randomized patients; the study reported the baseline characteristics of the study completers only