Intended isocaloric time-restricted eating shifts circadian clocks but does not improve cardiometabolic health in women with overweight.
Level 2 - randomized trial
Individual randomized crossover trial
PubMed 41160666 · doi:10.1126/scitranslmed.adv6787
What was done
A randomized crossover trial in 31 women with overweight or obesity compared 2 weeks of early time-restricted eating (eTRE; eating window 8:00 to 16:00) with 2 weeks of late time-restricted eating (lTRE; eating window 13:00 to 21:00). Participants were asked to maintain their habitual food quality and quantity during the 8-hour eating periods to keep intake isocaloric. Outcomes assessed included insulin sensitivity, 24-hour glucose, lipid profiles, inflammatory and oxidative stress markers, sleep midpoint, and circadian phase in blood monocytes.
What was found
Insulin sensitivity showed no significant difference between eTRE and lTRE (-0.07; 95% CI, -0.77 to 0.62; P = 0.60), nor within eTRE (0.31; 95% CI, -0.14 to 0.76; P = 0.11) or lTRE (0.19; 95% CI, -0.22 to 0.60; P = 0.25). No clinically meaningful between- or within-intervention differences were detected for 24-hour glucose, lipids, inflammatory markers, or oxidative stress markers. Adherence to eating windows was high (eTRE: 96.5%; lTRE: 97.7%). Dietary composition and physical activity remained unchanged, while modest weight loss (eTRE: -1.08 kg; lTRE: -0.44 kg) and a minor daily calorie deficit (eTRE: -167 kcal/day) occurred. Sleep midpoint occurred 15 minutes later during lTRE versus eTRE (95% CI, 7 to 23 minutes; P < 0.001), and monocyte circadian phase occurred 24 minutes later (95% CI, -5 to 54 minutes; P = 0.10).
Why it matters
This trial suggests that in an intended isocaloric setting, time-restricted eating does not improve cardiometabolic risk markers or insulin sensitivity regardless of whether meals are consumed earlier or later in the day.
Limits
The study had a short intervention duration (2 weeks per arm), a small sample size (n = 31), and included only women with overweight or obesity. A minor unintended caloric deficit and small weight change occurred despite the intended isocaloric design.
Cited by
- supports When calories are equated, the weight loss benefits of time-restricted eating are no longer observed.