Early Time-Restricted Feeding Improves Insulin
Sensitivity, Blood Pressure, and Oxidative Stress Even without Weight Loss in Men with Prediabetes
Restricted feeding benefits insulin sensitivity, blood pressure and oxidative stress in men with prediabetes.
Intermittent fasting (IF) improves cardio metabolic health; however, it is unknown whether these effects are due solely to weight loss. We conducted the first supervised controlled feeding trial to test whether IF has benefits independent of weight loss by feeding participants enough food to maintain their weight. Our proof-of-concept study also constitutes the first trial of early time-restricted feeding (eTRF), a form of IF that involves eating early in the day to be in alignment with circadian rhythms in metabolism. Men with prediabetes were randomized to eTRF (6-hr feeding period, with dinner before 3 p.m.) or a control schedule (12-hr feeding period) for 5 weeks and later crossed over to the other schedule. eTRF improved insulin sensitivity, b cell responsiveness, blood pressure, oxidative stress, and appetite. We demonstrate for the first time in humans that eTRF improves some aspects of cardiometabolic health and that IF’s effects are not solely due to weight loss.
In conclusion, 5 weeks of eTRF improved insulin levels, insulin sensitivity, b cell responsiveness, blood pressure, and oxidative stress levels in men with prediabetes – even though food intake was matched to the control arm and no weight loss occurred. Our trial was the first randomized controlled trial to show that IF has benefits independent of food intake and weight loss in humans. Our study was also the first clinical trial to test eTRF in humans and to show that eTRF improves some aspects of cardiometabolic health. Our trial tested eTRF in men with prediabetes – a population at great risk of developing diabetes – and indicates that eTRF is an efficacious strategy for treating both prediabetes and likely also prehypertension. We speculate that eTRF – by virtue of combining daily intermittent fasting and eating in alignment with circadian rhythms in metabolism – will prove to be a particularly efficacious form of IF. In light of these promising results, future research is needed to better elucidate the mechanisms behind both intermittent fasting and meal timing, to determine which forms of IF and meal timing are efficacious, and to translate them into effective interventions for the general population.