Anyone familiar with my blog, or me, will know that I have a pretty fair obsession with intermittent fasting for what are becoming more reasons than I can easily count. So what is particularly interesting about this paper, contrary to other papers where they have animals or people start fasting to prevent problems, this one found it helped after the fact. Intermittent fasting (alternate day fasting) was started 2 weeks AFTER an experimental heart attack was induced and was continued for 6 weeks. The beneficial effects were what I would call HUGE. Reference & abstract below, followed by my comments:
Chronic intermittent fasting improves the survival following large myocardial ischemia by activation of BDNF/VEGF/PI3K signaling pathway. Katare RG, Kakinuma Y, Arikawa M, Yamasaki F, Sato T. J Mol Cell Cardiol. 2009 Mar;46(3):405-12.
Chronic heart failure (CHF) is the major cause of death in the developed countries. Calorie restriction is known to improve the recovery in these patients; however, the exact mechanism behind this protective effect is unknown. Here we demonstrate the activation of cell survival PI3kinase/Akt and VEGF pathway as the mechanism behind the protection induced by intermittent fasting in a rat model of established chronic myocardial ischemia (MI). Chronic MI was induced in rats by occlusion of the left coronary artery. Two weeks later, the rats were randomly assigned to a normal feeding group (MI-NF) and an alternate-day feeding group (MI-IF). After 6 weeks of observation, we evaluated the effect of intermittent fasting on cellular and ventricular remodeling and long-term survival after CHF. Compared with the normally fed group, intermittent fasting markedly improved the survival of rats with CHF (88.5% versus 23% survival, P<0.05). The heart weight body weight ratio was significantly less in the MI-IF group compared to the MI-NF group (3.4+/-0.17 versus 3.9+/-0.18, P<0.05). Isolated heart perfusion studies exhibited well preserved cardiac functions in the MI-IF group compared to the MI-NF group (P<0.05). Molecular studies revealed the upregulation of angiogenic factors such asHIF-1-alpha (3010+/-350% versus 650+/-151%), BDNF (523+/-32% versus 110+/-12%), and VEGF (450+/-21% versus 170+/-30%) in the fasted hearts. Immunohistochemical studies confirmed increased capillary density (P<0.001) in the border area of the ischemic myocardium and synthesis VEGF by cardiomyocytes. Moreover fasting also upregulated the expression of other anti-apoptotic factors such as Akt and Bcl-2 and reduced the TUNEL positive apoptotic nuclei in the border zone. Chronic intermittent fasting markedly improves the long-term survival after CHF by activation through its pro-angiogenic, anti-apoptotic and anti-remodeling effects.
This was a rat study. Apparently people won’t submit to having one of their coronary arteries pinched off to see what happens with various eating plans. A number of things are interesting about this paper, not the least of which was 88.5% of the fasting rats survived compared to only 23% of the control group. That’s not exactly a subtle difference. Also I have read a number of papers and linked a Ted Talk by Mark Mattson, head of the National Institute on Aging, in which he talks about the positive effects of brain derived neurotrophic factor (BDNF) on the brain from both exercise and fasting. This paper suggests that the BDNF acts on the heart by increasing vascular endothelial growth factor (VEGF) thus stimulating the growth of new blood vessels in the heart (aka angiogenesis) improving circulation improves. They also noted lessened scar tissue formation and cardiac tissue hypertrophy, the combination of all factors greatly increased survivability. There was more to it than that, with the whole paper being a fascinating read.
I’m more a fan of the “time restricted feeding” variety of intermittent fasting, as I think alternate day fasting sounds particularly arduous. In spite of the health benefits, papers I have read describing people following alternate day fasting reported they never really got used to it, and continued to complain of hunger. I think for most people alternate day fasting is not a workable long term solution. However, I’m almost 9 months into what is currently a 20/4 (20 hour daily fast and 4 hour eating window) and it’s a piece of cake (but only after 5 pm). Fortunately, time restricted feeding with a 16/8 seems showing similar health improvements as alternate day diets. Personally I hadn’t heard about the 16/8 window until after I had read the Warrior Diet and Fast-5 (which is FREE) books. At that point, going back to 16/8 seemed like a reversal and not that different from what I was already doing since college by skipping breakfast. Once switching to the Fast-5 eating plan I reduced my total cholesterol 41 points in 43 days.
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Chad Reilly is a Physical Therapist, obtaining his Master’s in Physical Therapy from Northern Arizona University. He graduated Summa Cum Laude with a B.S. Exercise Science also from NAU. He is a Certified Strength and Conditioning Specialist, and holds a USA Weightlifting Club Coach Certification as well as a NASM Personal Training Certificate. Chad completed Yoga Teacher Training at Sampoorna Yoga in Goa, India.