Time-Restricted Feeding, Circadian Rhythms, and CVD

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Intermittent fasting strategies, including time-restricted feeding* interventions, have a range of health benefits, including the improvement of precursors to cardiovascular disease such as obesity, hypertension, dyslipidemia, and diabetes.1,2 Studies suggest that intermittent fasting treatments may improve health through multiple pathways, potentially reducing oxidative stress,2 enhancing mitochondrial health and DNA repair,1 and triggering autophagy,1 a cellular recycling system with a possible therapeutic role in some inflammatory diseases.3 And specific timing patterns of feeding and fasting windows may lead to greater improvement of cardiometabolic markers.4

Time-restricted feeding is a dietary pattern that optimizes circadian elements such as daily rhythms for insulin peaks and glucose tolerance5 by consuming food and beverages within a shortened window of time during the day, extending a person’s nightly fast to 12 hours or more. While there are limited large trials establishing an association between intermittent fasting interventions and improved cardiovascular disease outcomes, the available research suggests that in addition to reducing cardiovascular disease risk factors in healthy populations,2,4,6 time-restricted feeding may also hold promise as a beneficial adjunctive therapy, improving cardiometabolic health for some patients with metabolic syndrome.7

Early Time-Restricted Feeding

The circadian rhythms of the body influence sleep-wake cycles, eating and digestion patterns, and biochemical and metabolic processes.8 Studies suggest that interruptions to these biological rhythms and erratic eating patterns may lead to an elevated risk for chronic conditions, including cardiovascular diseases.8-10 For example, consuming more calories at breakfast may yield better health outcomes,11 while late-night meals may contribute to cardiovascular disease precursors such as obesity.12

Time-restricted feeding approaches consider these circadian elements, and in 2018, a small randomized controlled trial (RCT) with pre-diabetic participants was reportedly the first trial to investigate the impact of what researchers termed “early time-restricted feeding.”13 This intervention involved a six-hour eating period, no caloric restrictions, and dinner consumed before 3 pm. The control group followed a 12-hour eating window, and after a five-week intervention, compared to controls, the treatment group had reduced insulin levels and blood pressure without any reported weight loss. In addition, the treatment group showed improved insulin sensitivity and beta cell responsiveness.13

Additional small clinical trials published in 2019 also investigated the cardiometabolic and other biological impacts of early time-restricted feeding.14-16 Two of those studies also included a six-hour feeding window of 8 am to 2 pm. Compared to the 12-hour control feeding schedules, results indicated that the early time-restricted feeding treatments:

  • Decreased fasting glucose levels.15
  • Altered lipid metabolism15 and increased fat oxidation.16
  • Increased metabolic flexibility, defined as the ability to switch between the oxidation of different substrates.16
  • Increased a sense of fullness, decreased the desire to eat, and had no impact on 24-hour energy expenditure.16

Time-restricted feeding interventions that optimize circadian elements have the potential to improve patient outcomes through addressing the precursors of cardiovascular diseases and improving cardiometabolic health. Specific feeding windows and fasting lengths that yield the maximum health benefit continue to be studied; however, through the personalized approach of functional medicine care, flexible fasting strategies can be infused with various therapeutic nutritional interventions for each patient in order to create the most effective health treatment.

Learn more about nutrition and lifestyle strategies that positively impact cardiovascular outcomes at IFM’s Cardiometabolic Advanced Practice Module (APM).

*Of Note: Some experts define fasting as lasting 24 hours or more and do not consider time-restricted feeding a form of fasting.

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  2. Dong TA, Sandesara PB, Dhindsa DS, et al. Intermittent fasting: a heart healthy dietary pattern? Am J Med. 2020;133(8):901-907. doi:10.1016/j.amjmed.2020.03.030
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  7. Wilkinson MJ, Manoogian ENC, Zadourian A, et al. Ten-hour time-restricted eating reduces weight, blood pressure, and atherogenic lipids in patients with metabolic syndrome. Cell Metab. 2020;31(1):92-104.e5. doi:10.1016/j.cmet.2019.11.004
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  10. Manoogian ENC, Panda S. Circadian rhythms, time-restricted feeding, and healthy aging. Ageing Res Rev. 2017;39:59-67. doi:10.1016/j.arr.2016.12.006
  11. Nas A, Mirza N, Hägele F, et al. Impact of breakfast skipping compared with dinner skipping on regulation of energy balance and metabolic risk. Am J Clin Nutr. 2017;105(6):1351-1361. doi:10.3945/ajcn.116.151332
  12. Paoli A, Tinsley G, Bianco A, Moro T. The influence of meal frequency and timing on health in humans: the role of fasting. Nutrients. 2019;11(4):E719. doi:10.3390/nu11040719
  13. Sutton EF, Beyl R, Early KS, Cefalu WT, Ravussin E, Peterson CM. Early time-restricted feeding improves insulin sensitivity, blood pressure, and oxidative stress even without weight loss in men with prediabetes. Cell Metab. 2018;27(6):1212-1221.e3. doi:10.1016/j.cmet.2018.04.010
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  16. Ravussin E, Beyl RA, Poggiogalle E, Hsia DS, Peterson CM. Early time-restricted feeding reduces appetite and increases fat oxidation but does not affect energy expenditure in humans. Obesity (Silver Spring). 2019;27(8):1244-1254. doi:10.1002/oby.22518

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