What studies show the effectiveness of fasting?Updated a month ago
In periods of no insulin secretion, individuals experience 4-5 fold higher GH levels, from both more frequent pulse secretions, as well as higher pulse levels. This explains the muscle maintenance and fat loss seen in fasting, even over multiple days.
–Ho, K. Y., Veldhuis, J. D., Johnson, M. L., Furlanetto, R., Evans, W. S., Alberti, K. G., & Thorner, M. O. (1988). Fasting enhances growth hormone secretion and amplifies the complex rhythms of growth hormone secretion in man. The Journal of Clinical Investigation, 81(4), 968-975.
Henson et al. determined that even after 7 days of fasting, only nominal whole-body protein metabolization had occurred, and further research (2014) indicates that this is a loss of skin being metabolized via autophagy.
–HENSON, L. C., & HEBER, D. (1983). Whole body protein breakdown rates and hormonal adaptation in fasted obese subjects. The Journal of Clinical Endocrinology & Metabolism, 57(2), 316-319.
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Tashiro, K., Shishido, M., Fujimoto, K., Hirota, Y., Yo, K., Gomi, T., & Tanaka, Y. (2014). Age-related disruption of autophagy in dermal fibroblasts modulates extracellular matrix components. Biochemical and biophysical research communications, 443(1), 167-172.
Less than 50 calories of carbohydrates or protein will not create an insulin response that stops autophagy.
–Glynn, E. L., Fry, C. S., Drummond, M. J., Timmerman, K. L., Dhanani, S., Volpi, E., & Rasmussen, B. B. (2010). Excess leucine intake enhances muscle anabolic signaling but not net protein anabolism in young men and women. The Journal of nutrition, 140(11), 1970-1976.
Multiday fasting does not reduce physical performance capabilities.
–Knapik, J. J., Jones, B. H., Meredith, C., & Evans, W. J. (1987). Influence of a 3.5 day fast on physical performance. European journal of applied physiology and occupational physiology, 56(4), 428-432.
A time-restricted feeding regimen is a non-pharmacological strategy against obesity and associated diseases.
–100 Hatori, M, Vollmers, C, Zarrinpar A, DiTacchio L, Bushong EA, Gill S, Chaix A, Joens M, Fitzpatrick JAJ, Elisman MH, & Panda S. (2012). Time-restricted feeding without reducing caloric intake prevents metabolic diseases in mice fed a high-fat diet. Cell Metabolism. 15(6), 848-860.
The benefits of fasting appear to occur because after a sufficient period of time without food, a “metabolic switch” is flicked in the body. This typically occurs around twelve hours after your last meal, assuming you consume no further calories during that time.
–101 Anton, S. D., Moehl, K., Donahoo, W. T., Marosi, K., Lee, S. A., Mainous III, A. G., …& Mattson, M. P. (2018). Flipping the metabolic switch: understanding and applying the health benefits of fasting. Obesity, 26(2), 254-268.
Around twelve hours after your last food consumption, the body begins to break fatty acids into ketone bodies, which will become the new blood-borne chemical energy vector, replacing the glucose your body is running out of.
–102 Mattson MP, Longo VD, Harvie M. Impact of intermittent fasting on health and disease processes. Ageing Res Rev 2017;39:46-58.
While we would expect this metabolic switch to be “flipped” at the twelve-hour mark and the transition to ketosis to be initiated at that time, it may take a much longer fast of perhaps seventy-two hours for some individuals to transition completely to a ketogenic state.
–103 Scott, J. M., & Deuster, P. A. (2017). Ketones and Human Performance. Journal of Special Operations Medicine: a peer-reviewed Journal for SOF medical professionals, 17(2), 112-116.
Within twenty-four hours, the body will begin the process of autophagy, wherein it recycles and replaces old cells and cellular components. This process includes the destruction of misfolded proteins, the presence of which has been linked to Alzheimer’s and other diseases.
–104 Alirezaei, M., Kemball, C. C., Flynn, C. T., Wood, M. R., Whitton, J. L., & Kiosses, W. B. (2010). Shortterm fasting induces profound neuronal autophagy. Autophagy, 6(6), 702-710.
By the forty-eight-hour mark growth hormone levels peak, on average increasing to five times one’s baseline levels
–105 Hartman, M. L., Veldhuis, J. D., Johnson, M. L., Lee, M. M., Alberti, K. G., Samojlik, E., & Thorner, M. O. (1992). Augmented growth hormone (GH) secretory burst frequency and amplitude mediate enhanced GH secretion during a two-day fast in normal men. The Journal of Clinical Endocrinology & Metabolism, 74(4), 757-765.
–105 Hartman, M. L., Veldhuis, J. D., Johnson, M. L., Lee, M. M., Alberti, K. G., Samojlik, E., & Thorner, M. O. (1992). Augmented growth hormone (GH) secretory burst frequency and amplitude mediate enhanced GH secretion during a two-day fast in normal men. The Journal of Clinical Endocrinology & Metabolism, 74(4), 757-765.
At fifty hours, serum insulin, which has been trending downward since the onset of fasting, typically reaches its minimum level
–106 Klein, S., Sakurai, Y. O. I. C. H. I., Romijn, J. A., & Carroll, R. M. (1993). Progressive alterations in lipid and glucose metabolism during short-term fasting in young adult men. American Journal of Physiology Endocrinology and Metabolism, 265(5), E801-E806.
By the seventy-two-hour mark, the body has been triggered to recycle and replace all of its T-Cells, effectively regenerating a substantial part of the immune system and reversing immuno suppression
–107 Cheng, C. W., Adams, G. B., Perin, L., Wei, M., Zhou, X., Lam, B. S., …& Kopchick, J. J. (2014). Prolonged fasting reduces IGF-1/PKA to promote hematopoietic-stem-cell-based regeneration and reverse immunosuppression. Cell Stem Cell, 14(6), 810-823.
Intermittent fasting in healthy men looking to improve testosterone showed an improvement in fasting LH of nearly 67 percent, which in turn improved overall testosterone by an amazing 180 percent
–109 Röjdmark, S., Asplund, A., & Rössner, S. (1989). Pituitary-testicular axis in obese men during short-term fasting. European Journal of Endocrinology, 121(5), 727-732.
Other fasting research shows that temporary abstention from eating can dramatically assist in improving insulin sensitivity, which naturally promotes increases in testosterone by reducing the amount of insulin the body needs to release
–110 Sutton, E. F., Beyl, R., Early, K. S., Cefalu, W. T., Ravussin, E., & Peterson, C. M. (2018). Early time-restricted feeding improves insulin sensitivity, blood pressure, and oxidative stress even without weight loss in men with prediabetes. Cell Metabolism, 27(6), 1212-1221.
A 2010 study examined alternate daily fasting and found that fasting subjects were able to lose significant fat mass with no change in lean mass
–116 Bhutani, S., Klempel, M. C., Berger, R. A., & Varady, K. A. (2010). Improvements in coronary heart disease risk indicators by alternate-day fasting involve adipose tissue modulations. Obesity, 18(11), 2152-2159.
Research on daily sixteen-hour fasts performed in 2016 showed that participants in those fasts were also able to lose significant amounts of weight with no loss in muscle mass or maximal strength.
-117 Moro, T., Tinsley, G., Bianco, A., Marcolin, G., Pacelli, Q. F., Battaglia, G., …& Paoli, A. (2016). Effects of eight weeks of time-restricted feeding (16/8) on basal metabolism, maximal strength, body composition, inflammation, and cardiovascular risk factors in resistance-trained males. Journal of Translational Medicine, 14(1), 290.
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118 Catenacci, V. A., Pan, Z., Ostendorf, D., Brannon, S., Gozansky, W. S., Mattson, M. P., …& Troy Donahoo, W. (2016). A randomized pilot study comparing zero-calorie alternate-day fasting to daily caloric restriction in adults with obesity. Obesity, 24(9), 1874-1883.
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119 Trepanowski, J. F., Kroeger, C. M., Barnosky, A., Klempel, M. C., Bhutani, S., Hoddy, K. K., …& Ravussin, E. (2017). Effect of alternate-day fasting on weight loss, weight maintenance, and cardioprotection among metabolically healthy obese adults: a randomized clinical trial. JAMA Internal Medicine, 177(7), 930-938.
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Research done at USC in 2014 shows a seventy-two-hour fast triggers stem cell regeneration of T-Cells: 120 Cheng, C. W., Adams, G. B., Perin, L., Wei, M., Zhou, X., Lam, B. S., …& Kopchick, J. J. (2014). Prolonged fasting reduces IGF-1/PKA to promote hematopoietic-stem-cell-based regeneration and reverse immunosuppression. Cell Stem Cell, 14(6), 810-823.