THE QUICK READ
• Research indicates that time restricted-eating ( TRE ) can reduce blood glucose levels , improve insulin sensitivity , deplete glycogen stores , decrease oxidative stress and inflammation , lower blood pressure and improve sleep
• Data indicate a compressed eating window of between 6 to 8 hours can significantly improve health
• TRE aligns the supply of food with the time period during the day in which the body is best able to receive and use it
• Studies suggest that the physiologically ideal time for food consumption could be in the earlier hours of the day and in close proximity to exercise sessions
• TRE alters the pattern and frequency of protein ingestion in a manner that is not consistent with the current recommendations for protein intake and muscle health
• Studies have indicated that in order to prevent a reduction in muscle tissue , TRE requires adequate energy and protein intake to be combined with resistance training .
The benefits of TRE
All of the early knowledge on the benefits of TRE was derived from animal studies , which makes the extrapolation of recommendations to humans tenuous . However , the last several years have seen a number of trials conducted on a range of human subjects , including obese , normal weight and athletic males and females , allowing us to feel far more confident in our understanding of the benefits of this dietary approach .
Studies have shown that time-restricted eating can promote weight loss as well as health benefits independent of the reduction in body weight . Research indicates that TRE can reduce blood glucose levels , improve insulin sensitivity , deplete glycogen stores - which results in the elevation in circulating ketones - decrease systemic oxidative stress and inflammation , lower blood pressure and improve sleep patterns .
The ideal ratio
The ideal eating-to-fasting ratio is not currently known , but the totality of the data indicate a compressed eating window of between 6 to 8 hours ( fasting 16 to 18 hours ) can result in significant improvements to health outcomes . Interestingly , more time spent fasting is not necessarily better , with one study finding that reducing the feeding window to less than 6 hours did not confer additional benefits : obese adults implementing 4 hours ( 3 – 7pm ) or 6 hours ( 1 – 7pm ) of time-restricted eating for 8-weeks showed comparable reductions in body weight , caloric intake , oxidative stress , and improvements in insulin sensitivity .
In rhythm with the body
Time-restricted eating typically aims to align the feeding-fasting cycle with the light-dark periods of our circadian rhythms . This synchronises the supply of food with the time period during the day in which the body is best able to receive and use it .
Researchers have long noted a condition known as ‘ evening diabetes ’, where evening meals result in greater glucose and insulin spikes compared to the equivalent meal consumed in the morning . These findings have also been confirmed in other research to include poorer triglyceride control and weight regulation with late night eating . One study found that adults who consumed the majority of their calories in the morning showed more significant weight loss and decreases in waist circumference than those who consumed an equivalent amount of calories in the evening ,
Studies suggest that time-restricted eating causes positive effects on cardiometabolic parameters , particularly when food consumption occurs early in the day and in proximity to exercise and the active phases of the day .
It has been well noted that most of our modern society has almost uninterrupted access to food , especially products with high energy density and low nutritional quality , which has been shown to have negative health outcomes , especially with regards body weight and metabolic disease . The compressed eating window seen in TRE protocols causes a reduction in access to unrestrained food consumption , especially late night snacking .
From an evolutionary perspective , humans were highly active during the day and inactive overnight . In line with this , it appears that our circadian system has developed to ensure that physiological processes are most active during the day and conserved while we sleep . However , modern culture encourages behaviours that strongly contribute to circadian disruption , owing largely to artificial lighting , social jetlag , shift work , eating jet lag ( variability in the timing of food intake ), as well as the nearly uninterrupted access to food . All of this amounts to the development of numerous adverse health conditions .
In an attempt to investigate the effects of aligning food intake to the time of the day where we are most active , Elizabeth Sutton and her co-workers ( 2018 ) examined a specific type of time-restricted eating called early time-restricted eating ( eTRE ), in which feeding occurs early in the day to be optimally aligned with our biological circadian rhythms . The researchers showed that eTRE with a 6-hour eating period ( 8am to 2pm ) for a duration of five weeks showed improvements in insulin sensitivity and greater beta-pancreatic cells responsiveness , as well as important reductions in blood pressure levels , oxidative stress markers and hunger perception at night , compared to the control condition ( eating period of 12 hours ; 8am to 8pm ).
A potential concern of timerestricted eating is the potential to impair muscle mass and strength
12 | NETWORK SUMMER 2021