Table 1.
Time restricted studies in humans: experiment design and outcomes
| Study | Design | Participants | Baseline BMI (mean (SD)a | Age, y (mean (SD)) | TRE intervention; duration of intervention | Method of tracking temporal eating pattern/adherence | Adherence to TRE intervention (mean (SD)) | Baseline eating duration, h | TRE eating duration, h | Major findings, short version |
|---|---|---|---|---|---|---|---|---|---|---|
| LeCheminant et al, 2013 (118) | RXT | 27 Healthy M | 24.4 (2.5) | 20.9 (2.5) | 13-h TRE (6 am-7 pm, eliminated night time eating); 2 wk in each are w/ 1-wk washout | Self-reported and computerized multiple-pass 24 h recall (4 across 2-wk lead-in period) | 93.6% (5.6 %) (13/14 days). Self-reported | Not reported | Not reported | ↓ energy intake, body weight, and BMI, ↑ hunger on waking, no change in mood |
| Gill and Panda, 2015 (88) | Observation/pre-post | 156 (91 F) adults; intervention: 8 (3 F) adults with BMI > 25 and ≥ 14-h eating window | Observation: 24.74 (95% CI, 23.94-25.53); TRE: male: 31.77 (2.05); F: 34.91 (3.84) | 27.6 (26.4-28.8); intervention M: 34.4 (2.9); F: 36.3 (4.3) | 10-h TRE, self-selected; 16-wk w/1-y follow-up | myCircadianClock App: daily logging | Not reported | 95% eating window; Median 14.75 h | 10-12 h, (deceased by 4.32 h), actual eating duration not reported | ↓ body weight, BMI, hunger at bedtime, and energy intake, ↑ sleep satisfaction and energy level; No change in BMI in observation only (3 wk) |
| Moro et al, 2016 (96) | RCT | 34 M resistance-trained | a TRE: 26.5; Normal Diet: 27.2 | 29.21 (3.8) | 8-h TRE in 3 meals (1 pm, 4 pm, and 8 pm); Normal diet group had 3 meals (8 am, 1 pm, and 8 pm), both with diet and resistance training program; 8wks. | 7-d food diary validated by weekly structured interview with dietician to assess adherence to mealtime and diet composition | Not reported | Not reported | Not reported | ↓ fat-mass, IGF-1, and testosterone. No change in fat-free mass, muscle area of the arm and thigh, and maximal strength. |
| Tinsley et al, 2017 (119) | RCT | 18 M healthy young adult active | a 24.3 | 22 (2.4) | 4-hTRE(6pm-10pm) 4 d/wk (resistance training on nonrestricted eating d (3 d/wk); 8 wks | Dietary assessments at baseline, 4 wk, and 8 wk. Daily checklists completed on TRF days. | 80% compliance to TRE required to be included in analysis. Actual not reported | Not reported | Not reported | ↓ energy intake. No effect on lean mass retention or muscular improvement with training. |
| Antoni et al, 2018 (120) | NRCT | 13 (12 F) healthy adults; TRE = 7 (6 F), control = 6 (6 F) | a TRE: 29.0 (1.7); Control: 28.6 (2.8) | 29-57 (mean, SD not reported) | Shorten eating window by 3-h (delay first and advance last meal by 1.5 h each);10 wk | 4-day food diaries at baseline and wk 5 and 10 of intervention | 62.5% of d (2.5/4 d) | 12.4 h | 8.6 h | ↓ eating time and energy intake |
| Gabel et al., 2018; Gabel et al, 2019 (121, 122) | Pre-post with matched historical control with weight loss trial | TRE: 23 (20 F) adults with BMI 30-45; historical control 23(21 F) | TRE: 35.0 (1.0); control: 34.0 (1.0) | TRE: 50.0 (2.0); control: 48.0 (2.0) | 8-h TRE (10 am-6 pm); 12 wk | Daily adherence log (first and last calorie). And 7-d food journal during baseline and wk 12 of intervention | 80% of d, 5.6 (0.3) d/wk | 11 (1) h at baseline, self-reported | 8 (1) h | ↓ body weight and systolic blood pressure. No change in fat mass or fasting glucose. No adverse events |
| Gabel et al, 2020 (secondary analysis of (121)) (123) | Pre-post | 14 Adults with BMI 30-45 (sex not specified) | Weight: 94.85 (3.77) kg | 25-60 (mean, SD not reported) | 8-h TRE (10 am-6 pm); 12 wk | Daily adherence log (first and last calorie). And 7-d food journal during baseline and wk 12 of intervention | 80% of d, 5.6 (1.1) d/wk | Not reported | Not reported | ↓ body weight, fat mass, and systolic blood pressure, ↑ heart rate. No change in lean mass or gut microbiotic phylogenetic diversity. |
| Sutton et al, 2018 (75) | RXT | 8 (0 F) adults with prediabetes | 32.2 (4.4) | 56.0 (9.0) | 6-h early-TRE (3 meals starting 6:30-8:30 am); 12-h control (3 meals); 5 wks in each arm w/ 7-wk washout | All meals provided and consumed under supervision | 100% to TRE and 98.9% (1.8%) to control | Not reported | ≤ 6 h based on adherence (actual not reported) | ↑ insulin sensitivity and β-cell function, ↓ blood pressure, oxidative stress, evening appetite, and postprandial insulin. No change in body weight |
| Hutchison et al, 2019 (77) | RXT | 15 M (aged 30-70) with waist circumference ≥ 102 cm | 33.9 (0.8) | 55.0 (3.0) | 9-h TRE early and delayed (eTRE: 8 am to 5 pm; dTRE: noon-9 pm); 4 wk in each arm w/ 2-wk washout | Daily food diaries. | Not reported | ~ 9-15 h | 9 h assigned (actual not reported) | ↓ Glucose AUC (eTRE and dTRE, ↓ fasting glucose by CGM (eTRE) |
| Tinsley et al, 2019 (124) | Randomized, placebo-controlled-reduced factorial design | 40 (ITT)/24 (PP) resistance-trained women | TRE: 23.8; TREHMB: 22.9; Control: 22.5 | TRE: 22.1 (2.1); TREHMB: 22.3 (3.4); control: 22 (2.4) | 8-h TRE (noon-8 pm); 8 wk | Diet records at baseline and 2 follow-up assessments | Not reported. 80% compliance to TRE required to be included in PP analysis | Not reported | TRF: 7.5 (1.6) h; TRFHMB: 7.6 (0.7) h | ↓ fat mass in TRE and TREHMB in PP analysis, but not ITT. ↑ muscular performance in all groups |
| Ravussin et al, 2019, Jamshet et al, 2019 (76, 95) | RXT | 11 (4 F) adults with BMI 25-35 | 30.1 (2.7) | 32.0 (7.0) | 6-h eTRE: 8 am-2 pm (meals at 8 am, 11 am, and 2 pm), Control: 8 am-8 pm (meals at 8 am, 2 pm, and 8 pm); 4 d in each arm, 4- to 5-d washout | Not reported for the first 2 d. D 3 and 4 meals provided and consumption supervised | Not reported | Not reported | 6 h (in-lab d) Not reported for outpatient d | eTRE: ↓ mean 24-h glucose levels and glycemic excursions, ↑ MTOR expression, and altered lipid metabolism and circadian clock gene expression |
| Kesztyus et al, 2019 (125) | Pre-post | 40 (31 F) adults with ≥ 1 component of metabolic syndrome (63% on daily medication) | 31.3 (5.9) | 49.1 (12.4) | 8- to 9-h TRE; 12 wk | Daily food journal of first and last calorie. | 85% (15.2%) of d | 12.23 (2.27) h | 7.73 (0.82) h | ↓ weight, waist circumference, and HbA1c |
| Kesztyus et al, 2020 (secondary analysis of 2 studies) (126) | Secondary analysis of 2 pre-post studies (1 at university and 1 through general practitioner) | 99 (83 F) adults | 28.0 (5.7) | 48.9 (1.1) | 8- to 9-h TRE; 12 wk | Daily food journal of first and last calorie | 77.2% (18.7%) of d | University: 12.4 (1.8) h n = 61; general practitioner: 12.3 (1.2) h n = 38 | University: 8.4 (0.9) h n = 61; general practitioner: 7.7 (0.8) h n = 38 | ↑ quality of life and sleep quality |
| McAllister et al, 2019 (127) | Pre-post | 22 healthy M | 28.5 (8.3) | 22 (2.5) | 8-h TRE, self-selected (randomized to ad lib calorie or decreased by 300/d); 4 wk | MyFitnessPal and daily logging of time of first and last calorie | Not reported | Not reported | 7.2 (0.7) h | ↓ body fat, blood pressure, and ↑ adiponectin and HDL-c |
| Wilkinson and Manoogian et al, 2020 (91) | Pre-post | 19 (6 F) adults with metabolic syndrome and eating window ≥ 14 h | 33.06 (4.76) | 59 (11.14) | 10-h TRE, self-selected; 12 wk | myCircadian Clock App: daily logging | Participants outside their eating window by > 1 h on 7.13% (7.55) of days. | 95% eating window: 15.13 (1.13) h | 95% eating window: 10.78 (1.18) h | ↓ body weight, blood pressure, waist circumference, LDL cholesterol, non-HDL cholesterol, HbA1c, and ↑sleep restfulness in participants already on medication |
| Chow et al, 2020; Malaeb et al, 2020, Lobene et al, 2021; Crose et al, 2021 (117, 128-130) | RCT | 20 (17 F) adults with BMI ≥ 25 and eating window ≥ 14 h | 34.1 (7.5) | 45.5 (12.1) | 8-h TRE, self-selected; 12 wk | myCircadian Clock App: daily logging | 60% (23%) of d ± 30 min of eating window | 95% eating window: TRE (n = 11): 15.2 (0.7) h non-TRE (n = 9): 15.5 (1.1) h | 95% eating window: TRE (n = 11): 9.9 (2.0) h non-TRE (n = 9): 15.1 (1.1) h | ↓ body weight, lean mass, visceral fat; ↓ eating events and caffeinated beverages; TRE does not adversely alter bond turnover; ↑ quality of life |
| Zeb et al, 2020 (131) | RCT (2:1) | 80 young healthy M | TRE: 24.14 (3.5): control: 26.13 (5.2) | Not reported | 8-h TRE (19:30-03:30); 25 d | Not reported | Not reported | Not reported | Not reported | ↑ enrichment of microbiome, and circadian gene expression, improved lipid and liver profiles |
| Lowe et al, 2020 (132) | RCT (66 remote/50 local) | 116 (46 F) adults with BMI 27-43 | 32.7 (4.2) | 46.5 (10.5) | 8-h TRE (noon-8 pm); 12 wk | Smartphone App: asked participants daily if they were compliant with TRE | 22.8% (1128/4956 d) d reported in TRE and 22.7% (1088/4788 d) in control. Of reported d, 92.1% (1002/1088) in control; 83.5% (1128/1351) in TRE | Not reported | Not reported | ↓ body weight in TRE and control groups |
| Cienfuegos et al, 2020 (133) | RCT (3-arm) | 49 (5 F) adults with BMI 30-49.9 | b 4-h TRE: 36.0 (1.0); 6-h TRE: 37.0 (1.0); Control: 36.0 (1.0) | b 4-h: 49.0 (2.0 y); 6-h: 36.0 (3.0) y; 45 (2.0) y | 4-h TRE (3-7 pm), 6-h TRE (1 pm and 7 pm); 8 wk | Daily adherence log (first and last calorie) w/ weekly review with study coordinator | 89% for both groups, b4-h: 6.2 (0.02) d/wk; 6-h: 6.2 (0.1) d/wk | b 4-h: 13.2 (0.5) h (8-14h); 6-h: 13.4 (0.6) h (5-15 h) | Assumed intervention given high adherence | Similar results for 4- and 6-h TRE: ↓ body weight (–3.2% for both), insulin resistance, and oxidative stress for both TRE regimens produced compared to controls |
| Anton et al, 2019; Lee et al, 2020 (134, 135) | Pre-post | 10 (6 F) adults ≥ 65 and with BMI 25-45 | 34.1 (3.3) | 77.1 (SD not reported) | 8-h TRE (consistent timing not required), 12-h eating interval allowed first wk; 4 wks | Daily food journal of first and last calorie. | 84% of d | Not reported | Not Reported | ↓ body weight and BMI; TRE was safe and feasible for older adults with no change in energy levels while fasting |
| Parr et al, 2020; Lundell et al, 2020 (94, 136) | RXT | 11 M with BMI 27-35 | 32.2 (2.0) | 38.5 (5.0) | 8-h TRE (10 am, 1 pm, and 5 pm) and 15-h control (7 am, 2 pm, and 9 pm); 5 d each arm, w/ 10-d washout | Written food diary (3 d in each condition). | 6.7/10 self-reported score of ability to adhere to TRE (1 being not possible). Adherence to 5-d intervention not reported | Not reported | Not reported | TRE improved nocturnal glycemic control and was positively perceived. TRE affects rhythmicity of serum and muscle metabolites and regulates rhythmicity of genes controlling amino acid transport without disrupting clock gene expression |
| Parr et al, 2020 (137) | Pre-post | 19 (10 F) adults with T2DM (HbA1c > 6.5 and < 9%) and eating window > 12 h | 34.0 (5.0) | 50.0 (9.0) | 9-h TRE (10 am-7 pm); 4 wks | Written food diary or smartphone app (EasyDietDiary) to record all food entries. Photos of each food/beverage also taken using phone | 72% (24%), 5 d/wk | > 12 h, exact not reported | 72% adherent to 9-h eating window, exact not reported | TRE feasible and did not alter dietary intake, psychological well-being, or cognitive function. Focus should be on overcoming barriers. |
| de Oliveira Maranhão Pureza et al, 2020 (138) | RCT | 27 F (age 19-44 y) with low-income and BMI 30-45 | TRE + HD: 33.53 (4.53); HD: 33.12 (3.63) | TRE + HD: 31.03 (7.16); HD: 31.80 (6.96) | 12-h TRE with hypoenergetic diet (TRE + HD) or hypoenergetic diet only (HD); 12 mo | Three 24 h food records (2 work days, one weekend). Monthly meetings. | Not reported | Not reported | Not reported | Nonsignificant ↓ in % body fat, and waist circumference. Small ↑ in body temperature in TRE compared to control. No change in body weight |
| Martens et al, 2020 (139) | RXT | 22 (12 F) healthy midlife to older adults | 24.7 (0.6) | 67.0 (1.0) | 8-h TRE (self-selected w/ start 10-11 am); 6 wk | Daily electronic survey administered via email sent at 7 pm daily—participants reported first and last eating event | 84% to 8-h eating window, 95% were adherent to 8.5-h eating window | ~ 12 h, exact not reported | ~ 8 h, exact not reported | TRE safe, well-tolerated, and associated with high adherence and decreased hunger. No change in lean mass, bone density, nutrient intake, or cardiovascular function. Endurance and glucose tolerance modestly improved. |
| Kim et al, 2020 (140) | Pre-post | 15 (6 F) adults with BMI ≥ 25 | 29.3 (4.6) | 36.8 (8.44) | 8-h TRE (noon-8 pm), 2 provided meals/d; 4 wk | Called participants every morning to confirm compliance | Not reported | Not reported | Not reported | ↓ body weight; improvement of sleep apnea |
| Moro et al, 2020 (141) | RCT | 16 M elite cyclists | 21.85 (1.65) | 19.38 (2.39) | 8-h TRE (meals: 10-11 am, noon-1 pm, and 6-7 pm); control 7 am-9 pm (meals: 7-9 am, noon-1 pm, and 7-9 pm) and 1 snack w/ exercise for both groups; 4 wk | Dietician supervised most meals and ensured participants followed intervention | Not reported | Eating window not reported. Participants reported breakfast 7 am-9 am and dinner 7 pm-9 pm at baseline | Not reported | ↓ body weight, % fat mass, free testosterone, IGF-1, neutrophils to lymphocyte ratio, and ↑ peak power/body weight, ratio |
| Schroder et al, 2021 (142) | NRCT | 32 F with BMI ≥ 30 | TRE: 32.53 (1.13); control: 34.55 (1.20) | TRE: 36.6 (1.6); control: 42.3 (3.5) | 8-h TRE (noon-8 pm); 12 wk | Not assessed | Not reported | Not reported | Not reported | ↓ body weight, BMI, % body fat, waist circumference, and 30-y cardiovascular disease risk |
| Peeke et al, 2021 (143) | Virtual RCT | 60 (53 F) adults (18–65) with BMI ≥ 30 | 38.9 (7.7) | 44.0 (11.0) | TRE: 10-h TRE w/ snack at 12-h of fasting; active control: 12-h TRE. All participants on Jenny Craig diet (3 provided meals and 1 fruit snack/daily); 8 wk | Weekly phone visits and provided food | Not reported | Not reported | Not reported | TRE (14:10) ↓ body weight (within group and compared to 12:12 control) and ↓ fasting blood glucose (within group) |
| Przulj et al, 2021 (144) | Pre-post | 50 (37 F) adults with obesity with BMI ≥ 30 or >28 with comorbidities | 35.1 (4.0) | 50.1 (12.0) | 8-h TRE, self-selected; 12 wk | Clinic visits 1, 6, and 12 wk. Phone calls wk 2, 3, 4, and 5 | ~ 5 d/wk (wk 1-6, n = 32-47) and 5.1 (2.4) d/wk in wk 12 (n = 39) | Not reported | Not reported | ↓ body weight and hunger over intervention |
| Phillips et al, 2021 (145) | Observation and RCT | Observation: 213 adults (151 F) with BMI ≥ 20; RCT: 54. w />14-h eating window and ≥ 1 component of metabolic syndrome | Observation: 24.9 (22.6-29.1), RCT: 28.3 (24.6-30.5) | Observation: 40.1 (13.3), RCT: 43.4 (13.3) | Observation: 4 wk; RCT: 12-hTRE or standard dietary advice (SDA); 6 mo | myCircadianClock app: daily logging; phone or email reminders at 2 wk of observation phase and at 3 and 4 mo of intervention | Not reported | TRE: 15.48 (1.14) h, SDA: 15.17 (0.96) h | TRE: 12.50 (1.29) h, SDA: 14.89 (1.21) h | ↓ body weight (1.6%) |
| Domaszewski et al, 2020 (146) | RCT | 45 F age > 60 | All: 27.9 TRE: 28.99 (5.18); control: 26.99 (4.20) | 65 (5) | TRE: 8-h (noon-8 pm); 8 wk | Weekly diet reports from participants | 22/25 participants completed 6-wk program; excluded if not adherence for > 10% of intervention d | Not reported | Not reported | ↓ body weight, BMI, and fat mass, TRE better accepted than other forms of intermittent fasting |
| Jones et al, 2020 (147) | RCT | 16 healthy M | 24.0 (0.6) | 23 (1) | TRE: 8-h eTRE (8 am-4 pm), control/caloric restriction: matched to consumption of eTRE group; 2 wk | Food diaries throughout baseline and intervention | 1 event outside eating window, supported by CGM | TRE: 12.32 (0.25) h, control/CR: 11.33 (0.45) h | TRE: 6.87 (0.27) h, Control/CR: 11.68 (0.37) h | TRE improved whole-body insulin sensitivity and ↑ skeletal muscle glucose and BCAA uptake; ↓ energy intake and body weight matched in control/CR |
| Kesztyus et al, 2021 (148) | Pre-post | 63 adults (54 F), employed and without metabolic conditions (61 completed) | 26.1 (4.6) | 47.8 (10.5) | 8-9 h-TRE; 12 wk | Daily food journal of first and last calorie. | Fasting target reached 72.2% (18.9%) of recorded d | 12.42 (1.88) h | 8.38 (0.91) h | ↓ body weight and waist circumference, ↑ health-related quality of life, TRE was feasible and well accepted in working adults |
| McAllister et al, 2020 (149) | Pre-post | 16 M, resistance-trained firefighters | 21.3 (4.4) (n = 15) | 37 (6) (n = 15) | 10-h TRE; 6 wk | Zero smartphone app to document first and last food intake daily, or written food log and MyFitnessPal or food diary to track food intake. For 3-d pre- and post-TRF testing sessions | Not reported | 14.9 (0.2) h | 9.1 h (0.2 h) | ↓ advanced oxidation protein products and advanced glycated end products in blood |
| Pureza et al, 2020 (150) | RCT | 58 obese F living in social vulnerability | TRE (n = 31): 31.80 (29.25-34.36); control (n = 27): 31.03 (95% CI, 28.20-33.87) | TRE (n = 31): 33.53 (32.00-35.50); control (n = 27): 33.12 (95% CI, 31.68-34.56) | TRE: 12-h daily fasting (times could change) with hypoenergetic diet, control: hypoenergetic diet, 21 d, follow-up at 81 d | TRE: analog scale of difficulty. Eating pattern not monitored. For diet: 24-h dietary recalls (2 on weekdays and 1 on a weekend day), weekly consultations with dietician for 21 d, then every 2 wk until end of 81-d intervention | Not reported | Not reported | Not reported | ↓ body fat at 21 d and waist circumference at 81 d |
| Li et al, 2021 (151) | Pre-post | 15 F with PCOS | 29.75 (4.31) | 18-31 (mean and SD not provided) | 8-h TRE (8 am-4 pm); 5 wk | Food diary and record daily food intake in the Boohee software (diet and fitness app in China to calculate calories). Weekly phone calls | Not reported | Not reported | Not reported | ↓ body weight, BMI, body fat mass, body fat %, visceral fat area, total testosterone, sex hormone-binding globulin, free androgen index, fasting glucose, fasting insulin, HOMA-IR, AUCInsulin, AUCInsulin/AUCGlucose ratio, lipids, uric acid, ALT, hs-CRP, and IFG-1 |
| Prasad et al, 2021 (152) | Pre-post | 50 (41 F) adults (observation, 16 (TRE intervention) with BMI 25-50 and ≥ 14-h eating duration | Observation: 31.0 (10.8) | 51 (12) | 10-h TRE self-selected; 90 days. | myCircadianClock app: daily logging | 47% (19%) of d in intervention (daily logging and within eating window) | 95% eating window: observation (n = 50): 14.53 (2.60) h; TRE (n = 16): 16.07 (1.40) h | 95% eating window: TRE, n = 16: 11.90 (2.10) h | ↓ body weight, ↓ waist circumference, ↓ systolic blood pressure |
| Brady et al, 2021 (153) | RCT | 23 M middle- and long-distance runners | 23.6a | 36.4 (7.4) | 8-h TRE; 8 wk | Daily food log of eating windows. Full food diaries at baseline, 4 wk, and 8 wk | 94.5% (5.1) of d | Not reported | TRE: 7.9 (0.2) h, control: 12.9 (1.0) h | ↓ body weight and energy intake. No change in running performance or endurance |
| Bjerre et al, 2021 (154) | Pre-post interviews from TRE group of ongoing RCT (RESET study) | 17 (11 F) adults w/ BMI ≥ 30 and eating window of ≥ 12 h and at ≥ d/wk ≥ 14 | 32.9, range: 27.7-47.1 | 46-68 (11 > 60) | 10 h TRE, self-selected 6 am-8 pm; 12 wk | Food diary, 3 d (2 weekdays and 1 weekend) at baseline, 6 wk, and 12-wk | Self-reported: 100% for 2 participants, noncompliant 1-5 d/12 wk for 7 participants, noncompliant ≥ 1 d/wk for 8 participants | Not reported | Not reported | Participants had to rearrange daily activities to adhere to TRE. Easy for some and barrier for others. Participants delayed breakfast and advanced dinner by 1-2 h |
All TRE interventions are consistent eating windows unless noted.
Abbreviations: ALT, alanine aminotransferase; AUC, area under the curve; dTRE, delayed time-restricted eating; F, female; HbA1c, glycated hemoglobin A1c; HOMA-IR, homeostatic model assessment of insulin resistance; Hs-CRP, high-sensitivity C-reactive protein; IFG-1, insulin-like growth factor-1; ITT, intention to treat analysis; LDL, low-density lipoprotein; NRCT, nonrandomized control trial; M, male; PCOS, polycystic ovarian syndrome; PP, per protocol analysis; RCT, randomized controlled trial; RXT, randomized crossover trial; SOC, standard of care; TRE, time-restricted eating; TRF, time-restricted feeding; TRFHMB, TRF with 3 g/d of leucine metabolite b-hydroxy b-methylbutyrate. German Register for Clinical Trials (DRKS). NIH Clinicaltrials.gov Number (NCT). TREe/eTRE, early time-restricted eating; T2DM, type 2 diabetes mellitus.
a If BMI was not reported, BMI was calculated from reported height/weight. If height was not reported, weight was provided. CI is provided if that was reported in place of SD.
b Mean (SEM) reported in place of mean (SD). Eating duration is reported as daily average unless otherwise noted.