The fitness gurus that just regurgitate the headlines forget to consider that the studies were conducted on people with low body fat. There are hundreds of studies that show when an individuals body fat drops below optimal levels, some muscle mass is is consumed during exercise. For those of us with lard to spare, the chemistry is different. Firstly we burn through any glucose left in the blood, then the hormones tell the liver and muscles to release the glycogen stored in the liver and muscles. Once that is used up, excess fat is burnt.
When you exercise in a fasted state, your body is already releasing the growth hormone that is used to repair your body. This means that you can work at higher intensity levels, build more muscle and your body gets more efficient at burning stored fat for energy. You also release more fat oxidising enzymes, which is the scientific term for burning fat.
There are also studies that show that endurance athletes who train on an empty stomach perform significantly better on subsequent fed races, as their bodies learn to switch from burning food energy to fat stores during long endurance races.
For my own testing, I worked out on Friday after eating a balanced lunch and performed well. This morning I worked out at 10am, after not eating since 4pm yesterday and the post workout report from the gym's computer system showed that today's work out was at a higher intensity and I burnt around 23% more calories during my 45 minute workout. I know that my sample size of one is statistically insignificant, but I will switch between fasted and fed workouts and record the results to see if the data shows any significant variation in performance levels.
Working out hungry may not suit everyone, but if you feel it works for you, then stick with it. For any weight loss or fitness subject out there, there will be people that say it works and those that say it doesn't. We, the unfit masses, need to exercise our brains as well as our butts to sift through the good and bad science to find out what applies to us and what applies to the elite athletes, on whom most of the studies were based. Whatever you find, sitting at the computer reading about it, ain't gonna shift the excess pounds. Get up and get active.
The Science
Insulin, glucose, insulin resistance, and pancreatic cancer in male smokers. Stolzenberg-Solomon RZ, Graubard BI, et al. National Cancer Institute, Department of Health and Human Services, Rockville, MD, USA. Journal of the American Medical Association, 2005 Dec 14;294(22):2872-8. ⤴
Effect of intermittent fasting and refeeding on insulin action in healthy men. Halberg N, Henriksen M, et al. Dept. of Muscle Research Centre, The Panum Institute, University of Copenhagen, Denmark. Journal of Applied Physiology, 2005 Dec;99(6):2128-36 ⤴
The correlation between metabolic syndrome and prostatic diseases. De Nunzio C, Aronson W, et al. Department of Urology, Sant'Andrea Hospital, University La Sapienza, Rome, Italy. European Urology, 2012 Mar;61(3):560-70 ⤴
Insulin resistance and breast-cancer risk. Bruning PF, Bonfrèr JM, et al. The Netherlands Cancer Institute, Amsterdam, The Netherlands. Bruning PF, Bonfrèr JM, et al. The Netherlands Cancer Institute, Amsterdam, The Netherlands. International Journal of Cancer, 1992 Oct 21;52(4):511-6 ⤴
Insulin resistance and cancer: epidemiological evidence. Tsugane S, Inoue M. Cancer Science, 2010 May;101(5):1073-9. ⤴
Effect of intermittent fasting and refeeding on insulin action in healthy men. Halberg N, Henriksen M, et al. Dept. of Muscle Research Centre, The Panum Institute, University of Copenhagen, Denmark. Journal of Applied Physiology, 2005 Dec;99(6):2128-36. ⤴
Usefulness of routine periodic fasting to lower risk of coronary artery disease in patients undergoing coronary angiography. Horne BD, May HT, et al. Cardiovascular Department, Intermountain Medical Center, Murray, Utah, USA. American Journal of Cardiology, 2008 Oct 1;102(7):814-819. ⤴
Growth hormone increases muscle mass and strength but does not rejuvenate myofibrillar protein synthesis in healthy subjects over 60 years old. Welle S, Thornton C, et al. The Journal of Clinical Endocrinology and Metabolism, 1996 Sep;81(9):3239-43. ⤴
Growth hormone in health and disease: Long-term GH therapy--benefits and unanswered questions. Clemmons D. Nature Reviews Endocrinology, 2013 Jun;9(6):317-8 ⤴
Adult growth hormone deficiency - benefits, side effects, and risks of growth hormone replacement. Reed ML, Merriam GR. Geriatrics and Extended Care, VA Puget Sound Health Care System, Madigan Health Care System, Tacoma, WA, USA. Frontiers in Endocrinology (Lausanne), 2013 Jun 4;4:64. ⤴
Basal growth hormone concentration increased following a weight loss focused dietary intervention in older overweight and obese women. Miller GD, Nicklas BJ, et al. Department Health and Exercise Science, Wake Forest University, Winston-Salem, NC, USA. The Journal of Nutrition Health and Aging, 2012 Feb;16(2):169-74. ⤴
Sex differences in anxiety and depression: Role of testosterone. McHenry J, Carrier N, et al. Frontiers in Neuroendocrinology, 2014 Jan;35(1):42-57. ⤴
Beneficial and adverse effects of testosterone on the cardiovascular system in men. Ruige JB, Ouwens DM, et al. Journal of Clinical Endocrinology and Metabolism, 2013 Nov;98(11):4300-10. ⤴
Andropause or male menopause? Rationale for testosterone replacement therapy in older men with low testosterone levels. Cunningham GR. Endocrine Practice, 2013 Sep-Oct;19(5):847-52. ⤴
Effects of testosterone and progressive resistance exercise in healthy, highly functioning older men with low-normal testosterone levels. Hildreth KL, Barry DW, et al. The Journal of Clinical Endocrinology and Metabolism, 2013 May;98(5):1891-900. ⤴
Effects of Ramadan fasting on 60 min of endurance running performance in moderately trained men. Aziz AR, Wahid MF, et al. British Journal of Sports Medicine, 2010 Jun;44(7):516-21. ⤴
Hormonal responses and adaptations to resistance exercise and training. Kraemer WJ, Ratamess NA. Sports Medicine, 2005;35(4):339-61. ⤴
Testosterone physiology in resistance exercise and training: the up-stream regulatory elements. Vingren JL, Kraemer WJ, et al. Sports Medicine, 2010 Dec 1;40(12):1037-53. ⤴
Exercise in the fasted state facilitates fibre type-specific intramyocellular lipid breakdown and stimulates glycogen resynthesis in humans. De Bock K, Richter EA, et al. Journal of Physiology2005 Apr 15;564(Pt 2):649-60. ⤴
Increased p70s6k phosphorylation during intake of a protein-carbohydrate drink following resistance exercise in the fasted state. Deldicque L, De Bock K, et al. European Journal of Applied Physiology, 2010 Mar;108(4):791-800. ⤴
Metabolic responses to exercise after fasting. Dohm GL, Beeker RT, et al. Journal of Applied Physiology, 1986 Oct;61(4):1363-8 ⤴
Alternate-day fasting in nonobese subjects: effects on body weight, body composition, and energy metabolism. Heilbronn LK, Smith SR, et al. American Journal of Clinical Nutrition, 2005 Jan;81(1):69-73. ⤴
Training in the fasted state facilitates re-activation of eEF2 activity during recovery from endurance exercise. Van Proeyen K, De Bock K, et al. European Journal of Applied Physiology, 2011 Jul;111(7):1297-305. ⤴
Training in the fasted state improves glucose tolerance during fat-rich diet. Van Proeyen K, Szlufcik K, et al. 2010 Nov 1;588(Pt 21):4289-302. ⤴
Effect of training in the fasted state on metabolic responses during exercise with carbohydrate intake. De Bock K, Derave W, et al. Journal of Applied Physiology, 2008 Apr;104(4):1045-55. ⤴
Effects of caloric restriction and overnight fasting on cycling endurance performance. Ferguson LM, Rossi KA, et al. Ferguson LM, Rossi KA, et al. Journal of Strength and Conditioning Research, 2009 Mar;23(2):560-70. ⤴
Adaptations to skeletal muscle with endurance exercise training in the acutely fed versus overnight-fasted state. Stannard SR, Buckley AJ, et al. Journal of Science and Medicine in Sport, 2010 Jul;13(4):465-9. ⤴
Beneficial metabolic adaptations due to endurance exercise training in the fasted state. Van Proeyen K, Szlufcik K, et al. Journal of Applied Physiology, 2011 Jan;110(1):236-45. ⤴
Effects of caloric restriction and overnight fasting on cycling endurance performance. Ferguson LM, Rossi KA, et al. Ferguson LM, Rossi KA, et al. Journal of Strength and Conditioning Research, 2009 Mar;23(2):560-70. ⤴
Using molecular classification to predict gains in maximal aerobic capacity following endurance exercise training in humans. Timmons, J.A., Knudsen, S., Rankinen, T., et al. Panum Institutet and Center for Healthy Ageing, Faculty of Health Sciences, University of Copenhagen, Copenhagen, Denmark. Journal of Applied Physiology, 2010 Jun;108(6):1487-96. Epub 2010 Feb 4 ⤴
Effects of Ramadan fasting on 60 min of endurance running performance in moderately trained men. Aziz AR, Wahid MF, et al. British Journal of Sports Medicine, 2010 Jun;44(7):516-21. ⤴
The effect of ramadan fasting on physical performances, mood state and perceived exertion in young footballers. Chtourou H, Hammouda O, et al. Asian Journal of Sports Medicine, 2011 Sep;2(3):177-85. ⤴
Ramadan fastings effect on plasma leptin, adiponectin concentrations, and body composition in trained young men. Bouhlel E, Denguezli M, et al. International Journal of Sport Nutrition and Exercise Metabolism, 2008 Dec;18(6):617-27. ⤴
Effect of carbohydrate ingestion during exercise on post-exercise substrate oxidation and energy intake. Melby CL, Osterberg KL, et al. International Journal of Sport Nutrition and Exercise Metabolism, 2002 Sep;12(3):294-309. ⤴
The protein-retaining effects of growth hormone during fasting involve inhibition of muscle-protein breakdown. Nørrelund H, Nair KS, et al. Diabetes. 2001 Jan;50(1):96-104. ⤴
Intermittent fasting does not affect whole-body glucose, lipid, or protein metabolism. Soeters MR, Lammers NM, et al. American Journal of Clinical Nutrition, 2009 Nov;90(5):1244-51. ⤴
Protein feeding pattern does not affect protein retention in young women. Arnal MA, Mosoni L, et al. Journal of Nutrition, 2000 Jul;130(7):1700-4. ⤴
A controlled trial of reduced meal frequency without caloric restriction in healthy, normal-weight, middle-aged adults. Stote KS, Baer DJ, et al. American Journal of Clinical Nutrition, 2007 Apr;85(4):981-8. ⤴
Protein pulse feeding improves protein retention in elderly women. Arnal MA, Mosoni L, et al. American Journal of Clinical Nutrition, 1999 Jun;69(6):1202-8. ⤴
Splanchnic and leg substrate exchange after ingestion of a natural mixed meal in humans. Capaldo B, Gastaldelli A, et al. Diabetes. 1999 May;48(5):958-66. ⤴
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