The Effect of Early Time-Restricted Eating vs Later Time-Restricted Eating on Weight Loss and Metabolic Health.
Level 1 - systematic review of randomized trials
Network meta-analysis of randomized controlled trials
PubMed 36702768 · doi:10.1210/clinem/dgad036
What was done
A systematic review and network meta-analysis searched PubMed, Embase, Web of Science, and Cochrane Library up to October 16, 2022, for randomized controlled trials (RCTs) evaluating early time-restricted eating (TRE), later TRE, or non-TRE in adults with overweight or obesity. Primary and secondary outcomes included body weight, glycemic parameters (such as HOMA-IR and fasting blood glucose), blood pressure, and lipid profiles.
What was found
Twelve RCTs comprising 730 adults were analyzed. Both early and later TRE moderately decreased body weight and insulin resistance (HOMA-IR) compared to non-TRE control. Early TRE led to a significantly greater reduction in insulin resistance than later TRE (-0.44; 95% CI, -0.86 to -0.02; P < .05). Weight loss did not differ significantly between early and later TRE (-0.31 kg; 95% CI, -1.15 to 0.53 kg; P > .05). Compared to non-TRE, early TRE (but not later TRE) yielded significant improvements in glycemic metabolism and blood pressure, though direct comparisons between early and later TRE showed no significant differences for fasting glucose, blood pressure, or lipid profiles.
Why it matters
Aligning the eating window earlier in the day may confer greater metabolic and insulin sensitivity benefits than later eating windows, independent of total weight loss.
Limits
The total sample size across 12 trials was relatively small (730 participants), limiting precision. The abstract does not define the specific hourly boundaries used to classify "early" versus "later" eating windows, intervention durations, dietary composition, or caloric intake controls.