4. Discussion
overweight, cardiovascular disease
OBESE, INSULIN RESISTANCE, CARDIOVASCULAR DISEASE
This report extends the original findings from our TRE study in endurance-trained athletes [The present study is one of just a few studies to investigate the effects of the 16/8 time-restricted eating diet in trained athletes. To our knowledge, there is only one other study conducted in endurance-trained athletes. Brady et al. [Moro et al. studied the 16/8 diet in resistance-trained males while maintaining similar caloric and macronutrient intake and in a similar design, Tinsley et al. investigated a 16/8 TRE diet combined with an 8-week resistance training program, but in resistance-trained female athletes [Interestingly, considering that the energy and macronutrient intake and running distance each week were not significantly different between interventions, a significant decrease in RER was not observed, indicating no significant shift to utilize more fat and less carbohydrate and/or glycogen. There was a slight observed decrease in RER with TRE, and it is conceivable that RER would have decreased significantly if the study duration was longer than 4 weeks or if the present study employed more subjects. Future studies should include a longer intervention to determine if dietary duration may affect this result.It should be noted that it does appear that maintaining energy intake is vital when adopting TRE to achieve goals related to loss of fat mass. The 650 kcal deficit reported in the Tinsley et al. study could cause the body to enter a “conservation mode” or “survival mode” where the body perceives starvation and will employ a number of metabolic adaptations, such as decreasing resting metabolic rate and improving metabolic efficiency, in an attempt to preserve energy and body fat [The primary objective of our study was to determine if the TRE diet intervention affected cardiometabolic variables differently than the response to the normal diet intervention. Traditional clinical markers of cardiovascular disease were not affected by TRE in the present study. This is not surprising because they were actively training, and longer bouts of aerobic exercise lead to greater reliance on free fatty acids for energy production [There is growing evidence to support the notion that TRE can be utilized to combat insulin resistance; however, this has primarily only been studied in overweight and obese populations [Several limitations to the present study should be discussed. For example, participants were allowed to choose the time frame for their window of eating. The window of eating was not standardized because a study by Hutchison et al. showed no difference in fasting glucose, insulin, triglycerides, non-esterified fatty acids or gastrointestinal hormones between early TRE (eating window 8 am to 5 pm) and delayed TRE (12 pm to 9 pm). While they did not examine a full lipid panel, this study provides some insight to the notion that the window of meal timing may not matter with TRE diets [