來源The Fasting Method電子報，2020-3-18
Fasting and COVID-19
A lot of people are worried about how fasting affects the risk of COVID-19 virus infection. The truth is there is no good information on this subject at all, so everything is a matter of speculation.
Here’s my take on it:
Fasting mostly affects metabolism and therefore does not directly affect the risk of viral infection or immunity. However, the people at highest risk of severe disease are those with high blood sugars and other medical conditions. If fasting allows you to manage those metabolic diseases better, then it is logical to assume (but not proven) fasting may help in this case.
In any infection, the body has a natural reaction to stop eating. This is called the ‘fasting instinct’ and we’ve all experienced it. When we get a bad cold, the last thing we want to do is eat. Our appetite is naturally suppressed, and we fast. This presumable is part of the body’s protective response to lock down the available blood sugar and to activate the sympathetic nervous system to support the fight against the infection. So, it is logical to assume (but not proven) fasting may help (somewhat) against any viral infection, but at the least it won’t be harmful.
There have been some people who have noticed during longer fasts (>48 hours) cortisol increases and this may suppress immunity. This increased cortisol is part of the general activation of the body, along with other hormones like growth hormone and norepinephrine, so the net effect on immunity is unknown. Further, some have pointed out some of the severity of COVID-19 is due to the overreaction of the body’s own immune system (called a cytokine storm) and a mildly depressed immune response over longer fasting may actually be protective. However, the net effect of all these theoretical concerns is unknown.
So, based on my clinical experience only, since no studies are available, here are my best guesses at what to do about fasting with COVID-19:
- Fasting for less than 36 hours is likely neutral to slightly beneficial.
- Fasting for greater than 36 hours is likely neutral.
- If you become sick with any illness, including COVID-19, listen to your body. If you feel hungry, eat. If you do not feel hungry, do not eat.
- If you are not sick, continue whatever fasting regimen you planned to do.
- If at any point, you feel things are getting worse, stop immediately.
Dr. Jason Fung