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. 2020 Jan 21;11:1–28. doi: 10.2147/OAJSM.S224919

Table 6.

Effect of Fasting on Metabolic Adaptations in Trained and Untrained Subjects

Author Study Population Study Design Main Findings
Lipid Metabolism Glucose Metabolism Protein Metabolism
Schübel et al (2018)29 150 overweight and obese (50% Male – 50% female) - CCR, n=49
- ICR, n=49
- CG, n=52.

  • Age: 35 to 65 years.

  • BMI: 25 to 40 kg/m2.

 →ICR: 5 days without energy restriction and 2days with 75% ↓ in energy needs→ CCR: 20% daily ↓ in energy needs
→CG: NC in calorie intake
(12 weeks intervention phase) (12 weeks maintenance phase) (26 weeks follow-up phase).		 NS change ↓ The glucose for CCR compared with ICR (P< 0.01) (at week 12).
NS difference between 3 groups (at week s 24–50)		 NM
Oh et al (2018)30 45 overweight and obese (26 Females- 19 Males):
-ADCR, n=13
-Exercise, n=10
-Exercise + ADCR, n=12)
-CG, n=10

  • Age: 18 to 64 years.

  • BMI: > 23.0 kg/m2.

 For 8 weeks
Exercise-ADCR and ADCR groups:
→ 3 Alternately fasted days (25% of daily energy intake, food consumed between 12 pm and 2 pm)
→ 4 Feed days (ad libitum)		 In ADCR group NS changes In ADCR group NS changes NM
Trepanowski et al (2017)18 100 obese adults (86 Females- 14 Males):
- ADF, n=34
- CR, n=35
- CG, n=31

  • Age: 18 to 64 years

  • BMI: ± 34

 For 1 year (6-month weight-loss + 6-month weight-maintenance):
→ADF: 25% of energy needs on fast days; 125% of energy needs on alternating “feast days”
→CR: 75% of energy needs every day
→CG: no-intervention		 NS change in TC and TG.
Just At month 6, ↑ HDL-C in ADF versus the daily CR (P<0.05)
Just at month 12, ↑ LDL-C in the ADF group (P<0.05)		 NS changes. NM
Aliasghari et al (2017)37 83 patients with NAFLD (57 Males – 26 Females):
-FG: n=42, Age: 37.59 ± 7.06 years
-NFG: n=41, Age: 35.8 ± 7.33 years.		 Ramadan fasting NS changes ↓ Fasting blood glucose (P<0.01) NM
Alsubheen et al (2017)47 17 healthy males:
-FG: n=9, Age: 32.2 ± 7.8 years
-NFG: n=8, Age: 35 ± 9.4years.		 Ramadan fasting NS change in TC NS changes NM
Bak et al (2016)79 18 healthy males
-Lean, n=9, BMI:19 to 23 kg/m2
-Obese, n=9, BMI: 32 to 40 kg/m2

  • Age: 20 to 35 years

 Examination on two occasions separated by a minimum of 21 days: 1) after an overnight fast of 12 h
2) after 72 h of fasting.		 In obese: ↑ whole body lipolysis ↓ in glucose for both groups (P < 0.01) Obese:↓ urea and amino acid fluxes both in the basal and 72-h fasted state.
↓ forearm muscle protein breakdown per 100 mL of forearm tissue, differences that persisted after 72 h of fasting
Syam et al (2016)80 43 volunteers (7 Males- 36 Females)

  • Age: 34.19 ± 11.25 years

  • BMI: 23.71 ± 3.96 kg/m2

 Ramadan fasting NM NM NS change in Protein body mass (−0.049 ± 0.170 kg, P=0.561)
Moro et al (2016)42 34 resistance-trained males:
-TRF, n= 17
-ND, n= 17

  • Age: 29.21 ± 3.8 years

  • Weight: 84.6 ± 6.2 kg

 For 8 weeks:
→TRF: 100% of their energy needs in an 8-h each day → three meals at 1 p.m., 4 p.m., and 8 p.m. and fasting period = 16h
(2826 ± 412.3 kcal/day, carbohydrates 53.2 ± 1.4%, fat 24.7 ± 3.1%, protein 22.1 ± 2.6%)
→ND: 100% of their energy needs three meals consumed at 8 a.m., 1 p.m., and 8 p.m. (3007 ± 444.7 kcal/day, carbohydrates 54.7 ± 2.2%, fat 23.9 ± 3.5%, protein 21.4 ± 1.8).		 In TRF:
↓ HDL-C (45.11 ± 5.89 to 58.06 ± 6.11 mg/dl) (p=0.014)
↓TG (54.11 ± 15.12 to 115.23 ± 11.77 mg/dl) (p=0.0052).
NS changes in TC and LDL-C.		 In TRF:
↓Glucose (96.64 ± 85.92 to 85.92± 7.13 mg/dl) (p=0.0011)		 NM
Gnanou et al (2015)53 20 healthy men
Age: 19–23 years.		 Ramadan fasting NM ↓ Blood glucose (p< 0.01) NM
Varady et al (2013)35 32 normal-weight and overweight (22 Females- 8 Males):
- ADF, n= 15
-CG, n=15

  • Age: 35 to 65 years

  • BMI between 20 and 29.9 kg/m2

 For 12 weeks
→ADF group alternated between fasting days (25% of kcal needs as determined by Mifflin equation; consumed between 12 pm and 2 pm) and ad libitum feeding days.		 In ADF group:
↓Triacylglycerol (20 ± 8%, P < 0.05)
↑ LDL particle size (4 ± 1 Å, P < 0.01)
NC in LDL-C, HDL-C		 NM NM
Bhutani et al (2013)32 83 obese (80 Females - 3 Males)
-E-ADF, n=18
-ADF, n=25
-Exercise, n=24
-CG, n=16

  • Age: 25 to 65 years

  • BMI: 30 to 39.9 kg/m2

 For 12 weeks
→ADF and E-ADF groups alternated between fasting days (25% of kcal needs as determined by Mifflin equation; consumed between 12 pm and 2 pm) and ad libitum feeding days.		 ↓ TC (p =0.053).
NS change in TG, HDL-C, LDL-C.		 NS change in blood glucose NC in C-reactive protein.
Eshghinia & Mohammadzadeh (2013)33 15 overweight and obese women.

  • Age: 33.46 ± 5.9 years.

  • BMI: 33.16 ± 5.02 kg/m2.

 For 6 weeks,
On 3 weekly fasting days; Saturday, Monday, and Thursday (25%– 30% of energy needs)
On 4 feeding days (1700–1800 kcal/d)		 NS changes NM NM
Teng et al (2013)25 56 Men:
- FCR, n=28
- CG, n=28.

  • Age: 50 to 70 years.

  • BMI: 23 to 29.9 kg/m2.

 For 12 weeks:
→ FCR: 300–500 kcal/d ↓ in caloric intake (For 2 non-consecutive days per week).
→CG: NC in energy needs		 A significant interaction effect in →TC (p<0.001)
→LDL-C (p<0.05)
→ (TC)/HDL (P<0.05)
NS effect in HDL and TG		 NS change NM
Klempel et al (2013)39 32 obese women:
-ADF-HF, n=17-ADF-LF, n=18

  • Age: 25–65 years.

  • BMI between 30 and 39.9 kg/m.2

 For 8 weeks
Alternated between fasting days (25% of kcal needs as determined by Mifflin equation; consumed between 12 pm and 2 pm) and ad libitum feeding days.
The two diets:
→ADF–HF (45% fat, 40% carbohydrate and 15% protein), →ADF–LF (25% fat, 60% carbohydrate and 15% protein).		 ↓ TC: 13 ± 2 and 16 ± 2% (P<0.0001) in the ADF–HF and ADF–LF.
↓ LDL-C: 18 ± 5 and 25 ± 3% (P<0.0001) in the ADF–HF and ADF–LF.
↓ TG: 14 ± 5 and 14 ± 4% (P<0.001) in the ADF–HF and ADF–LF.
NC in HDL-C in either group.		 NM NM
Mirzaei et al (2012)58 14 male collegiate wrestlers
(Age: 20.12±2.5 years).		 Ramadan fasting ↓TC (P=0.011)
↓ LDL-C (P=0.001).
↑ HDL-C (P=0.045).		 ↓ Blood glucose (p=0.001). NM
Shehab et al (2012)75 65 subjects
-42 Males (BMI: 28.1±4.4 kg/m2)
- 18 Females (BMI: 27.2 ±5.5 kg/m2).

  • Age: 38.7±10.5 years

 Ramadan fasting ↑HDL-C (P<0.001)
↓LDL-C (P< 0.001)
NS change in TC and TG		 NM NM
Nematy et al (2012)74

  1. Volunteers including


- 38 Males (Age: 29–70 years)
- 44 Females (Age: 54.0 ± 10 years)		 Ramadan fasting ↓TC(P = 0.02)
↓TG (P <0.001)
↓VLDL-C (P <0.001)
↓ LDL-C (P <0.001)
↓TC/HDL (P <0.001)
↓LDL/HDL ratio (P <0.001)
↑HDL-C (P <0.001)		 NS modification. NM
Varady et al (2011)40 59 overweight and obese (50 Females- 9 Males):
ADF, n=13
CR, n=12
Exercise, n=12
Control, n=12

  • Age: 35 to 65 years

  • BMI: 25 to 39.9 kg/m2

 For 12 weeks:
ADF and E-ADF groups alternated between fasting days (25% of kcal needs as determined by Mifflin equation; consumed between 12 pm and 2 pm) and ad libitum feeding days.		 In ADF:
NC in TC and HDL-C
↓LDL-C (P < 0.05) (10 ± 4%)
↓TG (P < 0.05) (17 ± 5%)		 NM NM
Varady et al (2009)34 60 obese (12 Females, 4 Males)

  • Age: 35–65 years.

  • BMI: 30 to 39.9 kg/m2.

 For 8 weeks:
Alteration between fasting days (25% of kcal needs as determined by Mifflin equation; consumed between 12 pm and 2 pm) and ad libitum feeding days.		 ↓TC −21 ± 4% (P < 0.01)
↓LDL-C −25 ± 10% (P< 0.01)
↓Triacylglycerol −32 ± 6% (P< 0.01)
NC in HDL-C		 NM NM
Chaouachi et al (2008)64 15 male elite judo athletes

  • Age 18 ± 1 years

 Ramadan fasting ↓TC (3.34 ± 0.26 to 3.72 ± 0.31 mmol • l –1) (P< 0.05)
↑HDL-C (1.30 ± 0.31 to 1.42 ± 0.28 mmol • l –1) (P < 0.01)
NC in LDL-C and TG.		 NC ↓ Protein from 77.1± 4.4 to 70.1 ± 4.3 g.l-1 (P < 0.01)
Ziaee et al (2006)81 81 healthy subjects (41 Males - 40 Females).

  • Age: 20–35 years

  • BMI: 21.2±4.5 kg/m2

 Ramadan fasting ↓HDL-C (P=0.001)
↑ LDL-C (P=0.045)
NS change in TC, TG and VLDL.		 ↓ Glucose (p=0.000) NM
Bouhlel et al (2006)67 9 trained men

  • Age: 19±2 years

  • BMI: 25.1±4.1 kg/m2

 Ramadan fasting NM NC ↑ Hemoglobin (P < 0.01)
Heilbronn et al (2005)82 16 healthy (8 Males- 8 Females)

  • Age: 20 and 55 years

  • BMI: 20.0 to 30.0 kg/m2

 ADF: fasting every other day for 22 days NM For females:
↓ Glucose (p= 0.01)
NC in insulin response
For males
NC in glucose
↓Insulin response (p= 0.03).		 NM
Fakhrzadeh et al (2003)73 91 subjects:
-50 Males(Age: 19.9±1.8 years and BMI: 21.8 ± 2.6 kg/m2)
-41 Females(Age: 21.9±3.9 years and BMI: 24.0 ± 4.5kg/m2)		 Ramadan fasting ↓TC (P< 0.001)
↓ TG (P<0.001 for men, P < 0.02 for woman)
↓LDL-C (P < 0.001)
↑HDL-C (P < 0.001)		 ↓Glucose in both men (P<0.0001) and women (P<0.0001). NM
Larijani et al (2003)83 67 male, 48 female adults

  • Age: 15 to 45 years

 Ramadan fasting NM ↓Glucose (88.4 ± 9.0 mg/dl to 62.9 ± 7.7 mg/dl) (p < 0.001). NM
Beltaifa et al (2002)76 26 athletes and 32 sedentary individuals Ramadan fasting NS modifications NC No significant change
Adlouni et al (1997)72 32 healthy men
(Age: 25–50 years)		 Ramadan fasting ↓TC: −7.9% (P< 0.001),
↓TG: −30% (P< 0.001)
↓LDL-C: −11.7% (P< 0.001)
↑HDL-C: −14.3%(P< 0.001).		 ↓ Blood glucose: 5.1 to 4.38 mmol/L (P < 0.001) NM

Abbreviations: ADCR, Alternate Day Caloric Restriction ADF, Alternate Day Fasting; ADF-HF, Alternate Day Fasting with High Fat ADF-LF, Alternate Day Fasting with Low Fat; BMI, Body Mass Index; CR, Caloric Restriction; CCR, Continuous Caloric Restriction; E-ADF, Exercise With Alternate Day Fasting; EX, Exercise; FCR, Fasting Caloric Restriction; FG, Fasting Group; HDL-C, High Density Lipoprotein; ICR, Intermittent Caloric Restriction; LDL-C, Low Density Lipoprotein; n, number; NC, No Change; ND, Normal Diet; NFG, Non Fasting Group; NM, Not Mentioned; NS, Non Significant; TC, Total Cholesterol; TG, Triglycerides; TRF, Time Restricted Feeding.