Is Intermittent Fasting Better Than Continuous Energy Restriction for Adults with Overweight and Obesity?

Figures & data

Table 1 Randomized Controlled Trials of IF and CR in Adults with Overweight and Obesity

Study, Y	Country	Participants	Duration	Intervention	Body Weight, % of Baseline Weight	VAT, % of Baseline	SAT, % of Baseline	Total Fat Mass, % of Baseline	Key result
ADF
Trepanowski et al,^Citation10 2017	USA	N = 100 (m = 14, f = 86), age 18~64 years; mean BMI 34 kg/m^2	12 months (6 months of weight-loss phase and 6 months of weight-maintenance phase)	ADF (fast day 25% intake and feed day 125% intake)	↓7.0% at 6 months; ↓5.0% at 12 months	NA	NA	NA	ADF did not produce superior adherence, weight loss, weight maintenance, or cardioprotection to CR
				CR (75% intake)	↓7.3% at 6 months; ↓4.5% at 12 months	NA	NA	NA
				Control (no-intervention)	↓0.7% at 6 months; ↑0.4% at 12 months	NA	NA	NA
Catenacci et al,^Citation25 2016	USA	N = 26 (m = 6, f = 20), age 18–55 years, BMI ≥30 kg/m^2	32 weeks (8 weeks of intervention + 24 weeks of unsupervised follow-up)	ADF (0-kcal fast day)	↓8.8% at 8 weeks; ↓5.9% at 32 weeks	NA	NA	↓1.1% at 8 weeks; ↓2.4% at 32 weeks	Similar decrease in weight loss, but IF better than CR to prevent weight regain
				CR (1500 kcal/d)	↓6.2% at 8 weeks; ↓4.4% at 32 weeks	NA	NA	↓1.0% at 8 weeks; ↓0.7% at 32 weeks
Trepanowski et al,^Citation26 2018	USA	N = 100 (m =14, f = 86), age 18~64 years; mean BMI, 34 kg/m^2	12 months (6 months of weight-loss phase and 6 months of weight-maintenance phase)	ADF (fast day 25% intake and feed day 125%)	↓7.0% at 6 months; ↓5.0% at 12 months	↓15.8% at 6 months; NA at 12 months	↑3.7% at 6 months; NA at 12 months	↓7.1% at 6 months; NA at 12 months	ADF and CR similarly increased the FFM:total mass ratio and decreased circulating leptin, without affecting the VAT:SAT ratio or other measured adipokines
				CR (75% intake)	↓7.3% at 6 months ↓4.5% at 12 months	↓13.0% at 6 months; NA at 12 months	↑3.9% at 6 months; NA at 12 months	↓7.1% at 6 months; NA at 12 months
				Control (no-intervention)	↓0.7% at 6 months ↑0.4%at 12 months	↓9.1% at 6 months; NA at 12 months	↑2.6% at 6 months; NA at 12 months	↓2.6% at 6 months; NA at 12 months
Coutinho et al,^Citation27 2018	Norway	N = 35, age 39 ± 9 years, BMI 36 ± 4 kg/m^2	12 weeks	ADF (3-day fasting 550 and 660 kcal; 4-day full caloric needs)	↓13% at 12 weeks	NA	NA	↓5.4% at 12 weeks	IF as effective as CR, similar in weight loss, body composition and compensatory responses activated with weight reduction.
				CR (33% reduction of the estimated energy needs)	↓12.1% at 12 weeks	NA	NA	↓5.2% at 12 weeks
Steger et al,^Citation28 2021	USA	N = 35, ages 21–65 years, BMI 31.2 ± 2.4 kg/m^2	24 weeks (12-week weight loss and12- week weight loss maintenance)	ADF (3-day fasting 550 and 800 kcal; 4-day healthy eating)	↓8.9% at 12 weeks; ↓10% at 24 weeks	NA	NA	↓4.1% at 12 weeks; ↓5.7% at 24 weeks	IF and CR result in similar weight loss, maintenance, and body composition changes.
				CR (1200~1600kcal)	↓10.4% at 12 weeks; ↓11.9% at 24 weeks	NA	NA	↓3.6% at 12 weeks; ↓5.3% at 24 weeks
The 5:2 diet
Carter et al,^Citation14 2018	Australia	N = 137 (m = 60, f = 77), with T2DM, age 61.0 ± 9.1 years; BMI, 36.0 ± 5.8 kg/m^2	12 months	5:2 fast day (500–600kcal)	↓6.8% at 12 months	↓9.1% at 12months	NA	↓11.8% at 12 months	Similar decrease in HbA1c level and weight with IF or CR
				CR (1200~1500kcal)	↓4.9% at 12 months	↓8% at 12 months	NA	↓8.1% at 12 months
Sundfør et al,^Citation15 2018	Norway	N = 112,(m =56, f = 56), age 21–70 years, BMI 30–45 kg/m^2	12 months (6 months of weight-loss phase and 6 months of weight-maintenance phase)	5:2 fast day (400/600 kcal for female/male)	↓8.4% at 6 months; ↓7.4% at 12months	NA	NA	NA	Weight loss and maintenance are similar in IF and CR,; IF has more pronounced hunger
				CR (1500kcal)	↓8.7% at 6 months; ↓8.4% at 12 months	NA	NA	NA
Schübel et al,^Citation29 2018	Germany	N = 150, (m = 75, f = 75), 25 ≤ BMI < 40, age 35–65 years	50 weeks (12-week intervention phase, 12-week maintenance phase, and 26-week follow-up phase)	5:2 fast day (75% reduction in energy needs)	↓7.1% at 12 weeks; ↓7.1% at 24 weeks; ↓5.2% at 50 weeks	↓22% at 12 weeks; NA at 24 weeks; ↓23% at 50 weeks	↓17% at 12 weeks; NA at 24 weeks; ↓12% at 50 weeks	NA	IF may be equivalent but not superior to CR for weight reduction and prevention of metabolic diseases
				CR (daily energy deficit ∼20%)	↓5.2% at 12 weeks; ↓5.5% at 24 weeks; ↓4.9% at 50 weeks	↓16% at 12 weeks; NA at 24 weeks; ↓19% at 50 weeks	↓12% at 12 weeks; NA at 24 weeks; ↓12% at 50 weeks	NA
				Control (no advice to restrict energy)	↓3.3% at 12 weeks; ↓3.3% at 24 weeks; ↓1.7% at 50 weeks	↓9% at 12 weeks; NA at 24 weeks; ↓6% at 50 weeks	↓8% at 12 weeks; NA at 24 weeks; ↓4% at 50 weeks	NA
Headland et al,^Citation30 2019	Australia	N = 244, ages 18–72 years, BMI ≥27 kg/m^2	52 weeks	5:2 fast day (500/600 kcal for female/male)	↓6.0% at 8 weeks; ↓5.7% at 52 weeks	NA	NA	↓9.6% at 8 weeks; ↓10.1% at 52 weeks	IF and CR have similar weight loss results at one year
				CR (1000/1200 kcal for female/male)	↓6.9% at 8 weeks; ↓7.4% at 52 weeks	NA	NA	↓11.2% at 8 weeks; ↓13.4% at 52 weeks
				WOWO (one-week restriction and one-week habitual diet)	↓6.4% at 16 weeks; ↓5.6% at 52 weeks	NA	NA	↓10% at 16 weeks; ↓10% at 52 weeks
Pinto et al,^Citation31 2020	England	N = 45, central obesity men and women, ages 35~75 years, with waist circumference >102 cm and >88 cm for men and women	4 weeks	5:2 fast day (48 h 600 kcal/d)	↓2.1% at 4 weeks	NA	NA	↓4.8% at 4 weeks	Similar decrease in weight loss and markers of cardiometabolic health
				CR (500 kcal/d reduction)	↓3.6% at 4 weeks	NA	NA	↓4.4% at 4 weeks
Opstad et al,^Citation32 2021	Norway	N = 112, abdominally obese subjects, aged 21~70 years, BMI 30~45 kg/m^2	12 months	5:2 fast day (400/600 kcal for female/male)	↓7.3% at 12 months	NA	NA	NA	Similar decrease in weight loss with 5:2 diet and CR.
				CR	↓8.3% at 12 months	NA	NA	NA
Conley et al,^Citation33 2018	Australia	N = 24: males aged 55–75 years, BMI ≥30 kg/m^2	6 months	5:2 fast day (600 kcal)	↓5.5% at 6 months	NA	NA	NA	The 5:2 diet was similar to CR for weight loss in the older male population and was well tolerated and effective.
				CR (500 kcal/d reduction)	↓5.4% at 6 months	NA	NA	NA
Pannen et al,^Citation34 2021	Germany	N = 98 (m = 50, f = 48), ages 35–65 years, BMI 25–39.9kg/m^2	102 weeks (12-wk intervention phase, 12-wk maintenance phase, and 26-wk follow-up phase, 52-wk follow-up phase)	5:2 fast day (25% of the isoenergetic energy requirement)	↓7.1% at 12 weeks; ↓7.1% at 24 weeks; ↓5.2%at 50 weeks; ↓4.3% at 102 weeks	NA	NA	NA	IF and CR were equivalent in achieving modest weight loss over two years. In the long term, more people seem to have difficulty following IF than CR.
				CR (80% of the individual energy requirement)	↓5.1% at 12 weeks; ↓5.6% at 24 weeks; ↓4.9% at 50 weeks; ↓5.0% at 102 weeks;	NA	NA	NA
				Control (no calorie restriction)	NA	NA	NA	NA
TRE
Lowe et al,^Citation23 2020	USA	N = 116 (m = 70, f = 46), ages 18~64 years, BMI 27 ~43kg/m^2	12 weeks	8-h TRE (12:00–20:00)	↓0.95% at 12 weeks	NA	NA	NA	No significant differences in weight loss, fat mass, fasting insulin, glucose, HbA1C, or blood lipids between two groups
				Control (no meal timing restrictions)	↓0.69% at 12 weeks	NA	NA	NA
Liu et al,^Citation24 2022	China	N = 118, ages 31.9 ± 9.1 years, BMI 28~45kg/m^2	12 months	8-h TRE (8:00–16:00)	↓10.6% at 6 months; ↓9.0% at 12 months	↓26.9% at 6 months; ↓21.3% at 12 months	↓22.4% at 6 months; ↓17.0% at 12 months	↓20.9% at 6 months; ↓17.9% at 12 months	Similar reduction in body weight, body fat, or metabolic risk factors with IF and CR, TRE can lead to weight loss, mainly attributed to CR
				CR (man 1500~1800 kcal, women 1200~1500kcal)	↓10.1% at 6 months; ↓7.2% at 12 months	↓25.1% at 6 months; ↓16.9% at 12 months	↓16.2% at 6 months; ↓12.2% at 12 months	↓19.3% at 6 months; ↓13.6% at 12 months
Isenmann et al,^Citation35 2021	Germany	N = 35, physically active individuals (m = 14, f = 21), ages 20~40 years, BMI 26~33kg/m^2	14weeks (8-week intervention phase and 6-week independent phase)	8-h TRE (12:00–20:00)	↓4.75% at 8 weeks; ↓4.75% at 14 weeks	NA	NA	↓14.99% at 8 weeks; ↓14.99% at 14 weeks	IF and CR have similar weight loss, fat mass and maintained LBM
				Control (healthy and balanced diet)	↓5.37% at 8 weeks; ↓5.37% at 14weeks	NA	NA	↓16.13% at 8 weeks; ↓16.13% at 14 weeks
Chow et al,^Citation36 2020	USA	N = 20 (m = 3, f = 17), ages 45.5 ± 12.1 years, BMI 34.1 ± 7.5kg/m^2	12 weeks	8-h TRE (self-selected)	↓3.8% at 12 weeks	↓17.6% at 12 weeks	NA	↓4.1% at 12 weeks	Compared to non-TRE, TRE decreased the weight, lean mass and visceral fat.
				Control (no meal timing restrictions)	↓1.5% at 12 weeks	0% at 12 weeks	NA	↓2.0% at 12 weeks
Thomas et al^Citation37 2022	USA	N = 81 (m = 12, f = 69), ages 38.0 ± 7.8 years, BMI 34.1 ± 5.7 kg/m^2	39 weeks (12W intervention, 27W follow-up)	10-h TRE +CR (self-selected starting within 3 hours of waking and 35% caloric restriction)	↓4.6% at 12 weeks; ↓5.2% at 39weeks	NA	NA	NA	Similar weight loss in the CR and TRE+CR.
				CR (35% caloric restriction)	↓4.0% at 12 weeks; ↓4.7% at 39 weeks	NA	NA	NA

Abbreviations: ADF, alternate day fasting; TRE, time restricted eating; CR, calorie restriction; VAT, visceral adipose tissue; SAT, subcutaneous adipose tissue; T2DM, type 2 diabetes mellitus; ↓, decrease in the indicated parameter; ↑, increase in the indicated parameter; NA, not applicable (parameter not measured).

Figure 1 Overall effects of IF versus CR.

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