"Early Time-Restricted Feeding Improves Insulin Sensitivity, Blood Pressure, and Oxidative Stress Even Without Weight Loss in Men with Prediabetes"
Sutton et al., 2018 | Cell Metabolism
Study Summary
This study investigated whether simply changing when we eat — without changing what or how much — can improve metabolic health. Researchers tested early time-restricted feeding (eTRF), where all meals are eaten within a 6-hour window earlier in the day.
Remarkably, they found that this shift alone led to better insulin sensitivity, lower blood pressure, and reduced oxidative stress, even when participants maintained their weight.
Experimental Design
- Participants: 8 men with prediabetes, overweight but otherwise healthy
- Design: Randomized crossover trial (each participant tried both eating patterns)
- Duration: Each condition lasted 5 weeks
- Feeding Schedules:
- eTRF: All calories consumed between 8 a.m. and 2 p.m. (6-hour window)
- Control: Same meals eaten between 8 a.m. and 8 p.m. (12-hour window)
- Caloric Intake: Identical between conditions — no dieting or weight loss involved
Key Findings
1. Improved Insulin Sensitivity
- Fasting insulin levels decreased with eTRF
- Participants showed significantly improved insulin sensitivity (HOMA-IR)
- Beta-cell function was enhanced
2. Lower Blood Pressure
- Systolic and diastolic blood pressure dropped by several points
- Improvements occurred even without weight loss or medication
3. Reduced Oxidative Stress
- Lower levels of 8-isoprostane, a marker of oxidative damage
- Suggests eTRF may protect cells from inflammation-related damage
4. Appetite Regulation
- Participants felt less hungry in the evening
- Reported better control over food cravings
Why It Matters
This study is one of the first human trials to show that
meal timing alone
— without calorie reduction — can positively influence metabolic health.
It supports the growing evidence that aligning food intake with our
biological clock (circadian rhythm)
can enhance health outcomes, especially for people at risk of type 2 diabetes.
Practical Takeaway
If you're not ready for major dietary changes, simply eating earlier in the day (e.g., finishing meals by 2–3 p.m.) could offer real metabolic benefits.