FitProven
Evidence Breakdown
Based on 3 studies
Evidence map
For & against, at a glance
RCT
Pro
Moro T et al. · 2016Journal of Translational Medicine8-week RCT in resistance-trained males comparing 16:8 time-restricted feeding to normal meal timing, both with matched caloric intake. The IF group lost significantly more fat mass while maintaining muscle mass. Testosterone and IGF-1 decreased in the IF group while adiponectin increased. Provides some evidence that IF may offer modest fat loss advantages in specific populations.
0.44
8-week RCT in resistance-trained males comparing 16:8 time-restricted feeding to normal meal timing, both with matched caloric intake. The IF group lost significantly more fat mass while maintaining muscle mass. Testosterone and IGF-1 decreased in the IF group while adiponectin increased. Provides some evidence that IF may offer modest fat loss advantages in specific populations.
Design RCT (0.8) × quality 0.55 = impact 0.44
View sourceMeta-Analysis
Con
Cioffi I et al. · 2018Journal of Translational MedicineSystematic review and meta-analysis of **11** randomised controlled trials (duration 8–24 weeks) comparing intermittent energy restriction (IER) with continuous energy restriction. All the intermittent regimens provided ≤ 25% of daily energy needs on "fast" days, but they differed in pattern (5:2 or other) and in what was allowed on "feed" days (ad libitum versus balanced intake).
The intermittent approach produced a comparable — not superior — result: weight loss WMD −0.61 kg (95% CI −1.70 to 0.47, p = 0.87) and percent weight loss WMD −0.38% (95% CI −1.16 to 0.40, p = 0.34). "No between-arms differences in the other variables were found," including body composition, blood pressure and the other cardiometabolic risk factors. The single exception was a slight reduction in fasting insulin favouring IER (WMD −0.89 µU/mL, 95% CI −1.56 to −0.22, p = 0.009), which the authors themselves say is of uncertain clinical relevance.
The authors conclude that both approaches "achieved a comparable effect in promoting weight-loss and metabolic improvements" and call for long-term trials. Intermittent fasting is a viable alternative to continuous dieting; it is not a better one.
0.75
Systematic review and meta-analysis of **11** randomised controlled trials (duration 8–24 weeks) comparing intermittent energy restriction (IER) with continuous energy restriction. All the intermittent regimens provided ≤ 25% of daily energy needs on "fast" days, but they differed in pattern (5:2 or other) and in what was allowed on "feed" days (ad libitum versus balanced intake). The intermittent approach produced a comparable — not superior — result: weight loss WMD −0.61 kg (95% CI −1.70 to 0.47, p = 0.87) and percent weight loss WMD −0.38% (95% CI −1.16 to 0.40, p = 0.34). "No between-arms differences in the other variables were found," including body composition, blood pressure and the other cardiometabolic risk factors. The single exception was a slight reduction in fasting insulin favouring IER (WMD −0.89 µU/mL, 95% CI −1.56 to −0.22, p = 0.009), which the authors themselves say is of uncertain clinical relevance. The authors conclude that both approaches "achieved a comparable effect in promoting weight-loss and metabolic improvements" and call for long-term trials. Intermittent fasting is a viable alternative to continuous dieting; it is not a better one.
Design Meta-Analysis (1.0) × quality 0.75 = impact 0.75
View sourceRCT
Con
Schoenfeld BJ et al. · 2014Journal of the International Society of Sports NutritionRCT comparing body composition changes in women performing fasted versus fed aerobic exercise over 4 weeks while in a caloric deficit. Both groups lost significant body mass and fat mass, but there were no significant differences between groups. The study did not support the claim that exercising in a fasted state enhances fat loss.
0.32
RCT comparing body composition changes in women performing fasted versus fed aerobic exercise over 4 weeks while in a caloric deficit. Both groups lost significant body mass and fat mass, but there were no significant differences between groups. The study did not support the claim that exercising in a fasted state enhances fat loss.
Design RCT (0.8) × quality 0.40 = impact 0.32
View sourceRCT
Pro
Moro T et al. · 2016Journal of Translational Medicine8-week RCT in resistance-trained males comparing 16:8 time-restricted feeding to normal meal timing, both with matched caloric intake. The IF group lost significantly more fat mass while maintaining muscle mass. Testosterone and IGF-1 decreased in the IF group while adiponectin increased. Provides some evidence that IF may offer modest fat loss advantages in specific populations.
0.44
8-week RCT in resistance-trained males comparing 16:8 time-restricted feeding to normal meal timing, both with matched caloric intake. The IF group lost significantly more fat mass while maintaining muscle mass. Testosterone and IGF-1 decreased in the IF group while adiponectin increased. Provides some evidence that IF may offer modest fat loss advantages in specific populations.
Design RCT (0.8) × quality 0.55 = impact 0.44
View sourceMeta-Analysis
Con
Cioffi I et al. · 2018Journal of Translational MedicineSystematic review and meta-analysis of **11** randomised controlled trials (duration 8–24 weeks) comparing intermittent energy restriction (IER) with continuous energy restriction. All the intermittent regimens provided ≤ 25% of daily energy needs on "fast" days, but they differed in pattern (5:2 or other) and in what was allowed on "feed" days (ad libitum versus balanced intake).
The intermittent approach produced a comparable — not superior — result: weight loss WMD −0.61 kg (95% CI −1.70 to 0.47, p = 0.87) and percent weight loss WMD −0.38% (95% CI −1.16 to 0.40, p = 0.34). "No between-arms differences in the other variables were found," including body composition, blood pressure and the other cardiometabolic risk factors. The single exception was a slight reduction in fasting insulin favouring IER (WMD −0.89 µU/mL, 95% CI −1.56 to −0.22, p = 0.009), which the authors themselves say is of uncertain clinical relevance.
The authors conclude that both approaches "achieved a comparable effect in promoting weight-loss and metabolic improvements" and call for long-term trials. Intermittent fasting is a viable alternative to continuous dieting; it is not a better one.
0.75
Systematic review and meta-analysis of **11** randomised controlled trials (duration 8–24 weeks) comparing intermittent energy restriction (IER) with continuous energy restriction. All the intermittent regimens provided ≤ 25% of daily energy needs on "fast" days, but they differed in pattern (5:2 or other) and in what was allowed on "feed" days (ad libitum versus balanced intake). The intermittent approach produced a comparable — not superior — result: weight loss WMD −0.61 kg (95% CI −1.70 to 0.47, p = 0.87) and percent weight loss WMD −0.38% (95% CI −1.16 to 0.40, p = 0.34). "No between-arms differences in the other variables were found," including body composition, blood pressure and the other cardiometabolic risk factors. The single exception was a slight reduction in fasting insulin favouring IER (WMD −0.89 µU/mL, 95% CI −1.56 to −0.22, p = 0.009), which the authors themselves say is of uncertain clinical relevance. The authors conclude that both approaches "achieved a comparable effect in promoting weight-loss and metabolic improvements" and call for long-term trials. Intermittent fasting is a viable alternative to continuous dieting; it is not a better one.
Design Meta-Analysis (1.0) × quality 0.75 = impact 0.75
View sourceRCT
Con
Schoenfeld BJ et al. · 2014Journal of the International Society of Sports NutritionRCT comparing body composition changes in women performing fasted versus fed aerobic exercise over 4 weeks while in a caloric deficit. Both groups lost significant body mass and fat mass, but there were no significant differences between groups. The study did not support the claim that exercising in a fasted state enhances fat loss.
0.32
RCT comparing body composition changes in women performing fasted versus fed aerobic exercise over 4 weeks while in a caloric deficit. Both groups lost significant body mass and fat mass, but there were no significant differences between groups. The study did not support the claim that exercising in a fasted state enhances fat loss.
Design RCT (0.8) × quality 0.40 = impact 0.32
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Evidence
PRO (1)
PRO RCTn=340.55 Moro T, Tinsley G et al. (2016)
the 16:8 group lost significantly more fat mass while maintaining muscle mass at matched calories; testosterone and IGF-1 decreased and adiponectin increased in the fasting group
8-week RCT in resistance-trained males comparing 16:8 time-restricted feeding to normal meal timing, both with matched caloric intake. The IF group lost significantly more fat mass while maintaining muscle mass. Testosterone and IGF-1 decreased in the IF group while adiponectin increased. Provides some evidence that IF may offer modest fat loss advantages in specific populations.
Weighted 0.55 — 34 resistance-trained men randomised (17 per arm) and 34 analysed — but there is no CONSORT flow diagram and no attrition statement, so the absence of dropouts is inferred from silence. Only 8 weeks, necessarily unblinded, and dietary intake was assessed by dietician interview: the authors concede real differences in energy or nutrient intake between groups may have existed, and that meal timing relative to training differed between arms — a confound for the very outcome measured. Funded from the authors' own institutional funds with no competing interests declared.
Funding: independent
Journal of Translational Medicine
AGAINST (2)
AGAINST Meta-Analysisn=5280.75 Cioffi I, Evangelista A et al. (2018)
No difference in weight loss between intermittent and continuous energy restriction: WMD -0.61 kg (95% CI -1.70 to 0.47, p = 0.87); percent weight loss WMD -0.38% (95% CI -1.16 to 0.40, p = 0.34). The one exception was a small drop in fasting insulin with intermittent restriction (WMD -0.89 uU/mL, 95% CI -1.56 to -0.22, p = 0.009), of uncertain clinical relevance
Systematic review and meta-analysis of 11 randomised controlled trials (duration 8–24 weeks) comparing intermittent energy restriction (IER) with continuous energy restriction. All the intermittent regimens provided ≤ 25% of daily energy needs on "fast" days, but they differed in pattern (5:2 or other) and in what was allowed on "feed" days (ad libitum versus balanced intake).
The intermittent approach produced a comparable — not superior — result: weight loss WMD −0.61 kg (95% CI −1.70 to 0.47, p = 0.87) and percent weight loss WMD −0.38% (95% CI −1.16 to 0.40, p = 0.34). "No between-arms differences in the other variables were found," including body composition, blood pressure and the other cardiometabolic risk factors. The single exception was a slight reduction in fasting insulin favouring IER (WMD −0.89 µU/mL, 95% CI −1.56 to −0.22, p = 0.009), which the authors themselves say is of uncertain clinical relevance.
The authors conclude that both approaches "achieved a comparable effect in promoting weight-loss and metabolic improvements" and call for long-term trials. Intermittent fasting is a viable alternative to continuous dieting; it is not a better one.
Weighted 0.75 — 528 participants analysed out of 630 enrolled across the pooled RCTs. Independently conducted with no competing interests, and a clean null with tight confidence intervals. Held below the top band because the pooled sample is modest, the component trials are short (8-24 weeks) and heterogeneous in how the intermittent arm was implemented, and dropout was substantial (102 of 630). Note the DOI recorded here (10.1093/nutrit/nux063) is wrong: the real paper is J Transl Med 2018;16:371, doi 10.1186/s12967-018-1748-4. The journal field is correct. The review pooled 11 trials, not the 12 previously recorded here.
Funding: none declared (no external funding; authors declared no competing interests)
Journal of Translational Medicine
AGAINST RCTn=20INDUSTRY0.40 Schoenfeld BJ, Aragon AA et al. (2014)
No significant between-group difference in body mass or fat mass loss between fasted and fed aerobic exercise; both groups lost fat, neither more than the other
RCT comparing body composition changes in women performing fasted versus fed aerobic exercise over 4 weeks while in a caloric deficit. Both groups lost significant body mass and fat mass, but there were no significant differences between groups. The study did not support the claim that exercising in a fasted state enhances fat loss.
Weighted 0.40 — n=20 analysed (10 fasted, 10 fed), 4 weeks only -- a short, small, single-site trial in young non-obese women, so it is underpowered to exclude a small effect and cannot speak to longer timeframes. Diet was self-reported; menstrual cycle not fully controlled. Product supplied in kind by a supplement manufacturer, though no cash funding and no competing interests declared. Treated as a small pilot-grade RCT.
Funding: Dymatize Nutrition (in-kind: supplied the meal-replacement shakes)
Journal of the International Society of Sports Nutrition