Unlike intermittent fasting (IF) – a dietary intervention that alternates between periods of abstaining from solid food intake (fasting), typically 2-3 days per week, time-restricted eating (TRE) – a derivative of IF – provides a daily time period for food intake, typically 4 to 12 hours per day.
The stark difference between IF and TRE is that TRE has no caloric restriction and affords a daily eating period.
The daily feeding period is considered to be from the start of the consumption of the first meal and extending to the completion of the last meal of the day. This eating time period is estimated, based on research of 15,000 American adults, to be 12 hours for most people – extending to 15 hours for some.
According to Food Timing, Circadian Rhythm and Chrononutrition: A Systematic review of Time-Restricted Eating’s Effects on Human Health, which appeared in the December 2020 issue of the online, peer-reviewed journal Nutrients , “a recent systematic review and meta-analysis of 19 studies showed that TRE leads to weight loss and a reduction in fat mass with a preservation of fat-free mass and also has beneficials effects on cardiometabolic parameters such as blood pressure, fasting glucose concentration and cholesterol profiles.”
The study authors, from the Department of General Medicine, Henri Warembourg Faculty of Medicine, University of Lille, France, reviewed the international literature, “exploring the effects of TRE on human health.”
In terms of adherence to TE and the effect on calorie consumption, it appears that TRE was well-tolerated – with a compliance of 80% in eight studies – which is driven by a diet’s ability to reduce the desire to eat, usually by increasing the fat or protein content.
From a metabolic perspective, the study authors cite research, which supports the fact that TRE may increase adiponectin, “an adipokine of which the secretion increases during fasting, and which could produce a loss of fat mass by increasing energy expenditure, and by activating AMPK, a kinase, which stimulates lipolysis (fat breakdown) and insulin-sensitivity.”
As it pertains to our circadian clock, the French reviewers state, “the circadian system represents all the physiological processes involved in a 24-h cycle, such as the sleep/wake cycle, blood pressure, heart rate, hormone secretion, cognitive performance and mood regulation.”
The system , comment the reviewers, “is regulated by a number of environmental stimuli, such as food intake, light exposure, and physical activity” – with any disruption contributing to numerous conditions, such as obesity.
Thus, note the reviewers, “limiting the time of food consumption seems to readjust the food intake with the circadian clock; this is a fundamental principle of chrononutrition, which is the study of relationships between circadian clocks and food intake, and which suggests that meal timing affects metabolism.”
Ongoing research is needed to fully understand and appreciate the effects of both IF and TRE on reducing the metabolic disease burden that many people encounter during a lifespan.
Depending on your health profile, it’s always best to consult with your primary care physician to determine of IF or TRE fits your health profile.
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