Is Fasting Bad?

Answered on August 19, 2014
Created November 13, 2011 at 7:40 PM

I know there are a lot of studies that show SHORT-TERM benefit in terms of fasting, but in the long-term there may be complications due to the alterations in hormones and the up-and-down from the fasting state to the usually large-post prandial state. In (01) there was no difference found in lean healthy men, however there was an alteration:

IF had no effect on the phosphorylation of AKT but significantly increased the phosphorylation of glycogen synthase kinase. Phosphorylation of mTOR was significantly lower after IF than after the SD.

(the mTOR phosphorylation could be bad since mTOR inhibition extends lifespan).

Here is a long-term study in rats (2):

However, whereas calorie restriction improved tissue redox state, food restriction and intermittent feedings did not. In fact, long-term intermittent feeding resulted in largely enhanced tissue release of oxidants. Overall, our results show that restricted diets are significantly different in their effects on glucose tolerance and redox state when adopted long-term. Furthermore, we show that intermittent feeding can lead to oxidative insulin receptor inactivation and glucose intolerance.

And again long term in rats (3):

Chronic ADF in rats results in development of diastolic dysfunction with diminished cardiac reserve. ADF is a novel and unique experimental model of diet-induced diastolic dysfunction. The deleterious effect of ADF in rats suggests that additional studies of ADF effects on cardiovascular functions in humans are warranted.

Do I currently fast? Yes I do, but only for 12-14 hours and if I ever feel like I went into ketosis, I break the fast with a small meal before eating my normal meal (also some aerobic exercise), thus hopefully returning insulin sensitivity and all that.


  1. Am J Clin Nutr. 2009 Nov;90(5):1244-51. Epub 2009 Sep 23.Intermittent fasting does not affect whole-body glucose, lipid, or protein metabolism.Soeters MR, Lammers NM, Dubbelhuis PF, Ackermans M, Jonkers-Schuitema CF, Fliers E, Sauerwein HP, Aerts JM, Serlie MJ.after the SD.

  2. Free Radic Biol Med. 2011 Oct 1;51(7):1454-60. Epub 2011 Jul 21.Long-term intermittent feeding, but not caloric restriction, leads to redox imbalance, insulin receptor nitration, and glucose intolerance.Cerqueira FM, da Cunha FM, Caldeira da Silva CC, Chausse B, Romano RL, Garcia CC, Colepicolo P, Medeiros MH, Kowaltowski AJ.intolerance.

  3. J Card Fail. 2010 Oct;16(10):843-53. Epub 2010 Jul 1. Chronic alternate-day fasting results in reduced diastolic compliance and diminished systolic reserve in rats. Ahmet I, Wan R, Mattson MP, Lakatta EG, Talan MI.warranted.



on November 13, 2011
at 07:57 PM

And better than going on a 5-year binge too.

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4 Answers



on November 13, 2011
at 08:18 PM

In the absence of definitive scientific consensus one way or the other, I say go by feel.


on November 13, 2011
at 11:37 PM

I have had great results of different kinds from intermittent fasting. It has broken weightloss plateaus, killed sugar cravings, and helped me with constipation. I haven't done it in a few weeks but plan to now that the holidays are coming. It also sharpens my mind, strangely enough.


on November 13, 2011
at 09:13 PM

I came accross this article...hope it helps.




on November 13, 2011
at 07:49 PM

bad compared to what?

i know that i feel and function better fasting for at least 15 hours each day. is this best for me? maybe not, but its better than grazing every 3-4 hours.

there are many shades of bad



on November 13, 2011
at 07:57 PM

And better than going on a 5-year binge too.

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