Why do I feel cold when fasting?

by (810) Updated January 16, 2014 at 8:21 AM Created January 06, 2011 at 5:50 PM

Hey folks. Whenever I fast, I feel cold. Does anyone else experience this? Is there anything that can be done to remedy it?

I've always become cold very easily, and attribute it to poor circulation. However, this is unexpected, and definitely unwanted.


BTW, when fasting, I wear the same clothes and am in the same environment as when I'm not fasting.


I usually fast for 8-20 hours. For example, I finished eating at 9pm last night, and probably won't eat again until 4-6pm today. During a fast, I consume nothing but water.

It's rare that I fast more than once a week. I try not to feast before a fast. After fasting, I usually eat ~25% extra food for that meal.

I'm male, 6'1", 160lbs, lean, and athletic, with 9-10% body fat, according to the Navy SEAL body fat calculator: http://fitness.bizcalcs.com/Calculator.asp?Calc=Body-Fat-Navy

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18383 · January 06, 2011 at 9:07 PM

Actually, fasting is known to reduce core body temperature, not just the extremities. Even just caloric restriction does this. It is accompanied, and probably caused, by a lowering of metabolic rate.

I don't know if this is good or bad in the long run. There are reasons to believe either. It's certainly uncomfortable, though -- I definitely notice it, too.

5330 · January 06, 2011 at 7:12 PM

Check out this link. http://www.leangains.com/2010/09/eat-stop-eat-expanded-edition-review.html

In the book review Martin has a section entitled "fasting and cold fingers"

The basic idea is that during fasting your blood circulation is centered around your abdomen and less blood circulation to the extremeties. He believes it is nothin to be worried about. It can be helpful (says Martin) because during the fast you are attempting to rid yourself of abdomen fat and the enhanced blood flow speeds this process. Don't take my word for it though, read the site.

I get cold sometimes when fasting. It seems to be happening less and less. My take is to put on warmer clothes and stick it out. Of course you should never do something you feel is harmful to your health. If you are having issues with fasting maybe you should start with a fast for a shorter period of time and extend it gradually over a few weeks to acclimate.

10750 · January 06, 2011 at 8:23 PM

I can get a bit cold during long fasts, i believe the body is just being careful with it's energy reserves. I don't see this as a problem, and it is even rather pleasant during the summers.

A quick spot of movement or exercise warms me back up. Wool socks can help, too.

30 · March 08, 2011 at 9:58 PM

Funny i stumbled across this today...yesterday i fasted for 24 hrs and at about hr 16 i too became cold and couldn't warm up, but actually was getting colder. I even turned the heat up in the house and the wife was super surprised. I am 6' 192lbs with 7% BF...all of thses answers make sense. Thnx for all the input hackers!

3482 · January 08, 2011 at 6:55 AM

When fasting your body is answering by conserving more energy and that translates in less body heat. That's a first common sign of the body in energy conservation mode. I you were to fast for an extended period of time, you would get even colder, then would have less and less energy and eventually even climbing stairs would seem like a chore.

This is normal, but I think that it can only get better with time and your body getting used to be efficient with its energy.

8185 · January 06, 2011 at 7:20 PM

Not really big on fasting, but for me, I've noticed I get cold a lot easier when I'm cutting the calories. I always attributed it to the metabolism running a bit more sluggishly without the extra calories.

0 · January 16, 2014 at 8:21 AM

Fast sometimes I have ,Yep there are some problems ,something like your body circumstances.Complicated ,if you like check here maybe there will provide some solutions.


0 · January 14, 2014 at 12:42 PM

Stumbled across this, possibly outdated by now, but anyway. I experience the same at the end of a 16 hour fast period (16/8 pattern). My explanation (being a MD by the way) is different: During fasting your body shows a slight shift in the balance of the autonomous nervous system towards the sympathetic side. This so called noradrenergic or adrenergic reaction leads to cold extremities due to less blood flow in the extremities. It also causes the nice feeling of being wide awake and alert. You can enhance (or worsen) the effect by the intake of caffeine (as in coffee).

0 · September 07, 2013 at 12:44 AM

I am freezing right now and I'm three hours from being done on a 24 hour. I have fingerless gloves on but I am so cold. I had to take a bath before bed and I just laid there for 2 hours shivering.

0 · April 03, 2013 at 11:57 AM

I seem to get really cold every time I eat. I have Raynauds's disease i.e. thick blood that finds it hard to reach the extremities. I'm having green tea for breakfast, poached eggs with spinach for lunch and whatever I like for dinner. I've just had my eggs and my body temperature has shot down and I can't feel my big toes, which have changed colour. Last two days I've had to have a bath after dinner to warm up. Its only four degrees outside but that's warmer than the last few weeks, although not all the snow has melted, it is sunny.

I just think what little energy I have is concentrated around digesting my food, but seriously, two eggs and some spinach, how much energy does that require?

0 · March 06, 2013 at 9:12 PM

I too get cold when fasting. I do daily 20/4 windows, and 16/8 windows on lifting days. Works ok for me though, since I live in the desert southwest and summers get into the 100+ temps. :)

Studies have shown that metabolism actually increases when fasting, at least during the first 24-72 hours. More info on that at leangains, just search for Top 10 Fasting Myths Debunked article. So, it's unlikely the coldness is due to reduced metabolism. Though I don't have an answer for it.

By the way, when I have my big pile-o-chicken breast at dinner, I warm up quickly. :)

0 · November 01, 2012 at 12:57 PM

Fasting reduces body-core Temp,the body conserves energy by pushing circulating blood to the major organs,this is logical and normal.Those with less than 10% body fat will feel it more. People may also notice an increase in blood pressure while others notice a drop in pressure. this is way fasts should be supervised by someone whom knows the warning signs for certain individuals that may get into potential serious problems.

Anyone whom has never fasted before or whom has known health issues should always be supervised and monitored by a health care professional.such clinics do exist such as true-north in the USA and I myself supervise individuals www.bodybudddha.co.uk.

0 · July 21, 2012 at 4:23 PM

im muslim and i'm fasting for about 18shours this ramadan, just googled cold and fasting and this came up.

why are you lot fasting is this part of your religion too?

my mates dad was a rastfarian and he would randomly fast because he said it's good for the body but this was not aa obligation of his religion.

91 · February 21, 2011 at 10:54 AM

A study by Johnson et al in 1982 showed that the subjects on a calorie restricted diet or intermittent fasting program were leaner and more active yet more vulnerable to cold. Fortunately, unlike, the small animals used in these tests, we have ample methods of keeping warm and this, although an expected side effect, is not to be concerning.

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