Is It Safe To Workout While Fasting?

Hello health champions. Is it safe to exercise  while you're fasting? What really happens in the  

body when you're doing fasting or intermittent  fasting? Where does the energy come from?  

Today I'm going to answer all those questions  plus a few questions you didn't even know you had  

but you've been wondering about ever since you  were a kid. Coming right up. Hey I'm Dr Ekberg I'm  

a holistic doctor and a former Olympic decathlete  and if you want to truly master health by  

understanding how the body really works make sure  you subscribe and hit that notification bell so  

that you can keep learning about how to get truly  healthy in order to talk about whether it's safe  

to exercise and fast we first have to understand  where does the energy actually come from and we  

have to get rid of a few myths you've always been  told things like if you don't eat any breakfast  

you won't have any energy make sure that you  get frequent snacks so you can boost your energy  

and you have to eat protein immediately after a  workout because otherwise you won't be able to  

build muscles and you should eat so that you feel  better but if you feel better after you eat was it  

actually the food you ate that made you feel  better or was it something else let's talk about  

the facts whenever you eat something it comes  down to your esophagus and it's gonna sit in your  

stomach for two to five hours your body is going  to work on it it's going to churn it it's going  

to massage this it's going to add enzymes and  hydrochloric acid but you're not going to utilize  

it because it's not ready for that the only thing  you can absorb to some degree in small amounts  

are things like water alcohol and glucose that  stuff goes out a little bit faster but if you  

eat a whole food a whole meal there's going to be  no alcohol obviously and there's going to be very  

very little glucose in there so if you eat fruit  then a tiny percentage of that fruit is glucose  

free glucose nothing else no fat no protein  and no molecule bigger than a single molecule  

is going to get absorbed that's going to happen  much later in the small intestine so it sits for  

two to five hours in the stomach then when it's  ready it moves into the small intestine that's  

this squiggly convoluted thing here and that's  where most of the nutrient absorption takes place  

but that's 4 to 12 hours after you ate the food  so here's the big question how come then that you  

feel better after eating how do you feel satisfied  how do you feel energized when you're not using  

any of that yet because the food stimulates  things it creates an expectancy in the body so  

you're stimulating hormones and you're starting  to break down glycogen to raise blood sugar and  

feel satisfied because the body knows hey i can  use up this glycogen because you just ate so I'm  

going to be able to fill up the stores in a little  bit and if all of this is true which it is then  

what about the nutrients for exercise what about  all the calories and all the energy and all the  

stuff you need for exercise well the same thing is  true it does not come from the food you just ate  

nutrients are absorbed in the small intestine 4  to 12 hours after you eat the food and what that  

means is that the energy that you're using in this  moment whether it's just for everyday activity  

or whether it's for exercise doesn't come from  the meal that you just had it comes from nutrient  

pools and you have glycogen that's the extra  glucose the extra carbohydrate you eat gets put  

together into glycogen and stored in the muscles  and liver and that'll last you 12 to 24 hours  

you have fat that will last you 1 to 12 months if  you're super skinny you still have about a month  

worth of fat that you could live off if you're  obese you could make it up to a year some vitamins  

that are water soluble will last you for a few  days or weeks but others even if they're water  

soluble or fat soluble like b12 or vitamin d will  last you for years the body has a way of storing  

them and protein which you don't want to use  for energy but you could will last you for weeks  

so we have to rethink this idea about eating  something to get energy your body asks you to  

eat you create hunger so that you can keep up with  your energy expenditure but what you're eating now  

is going to be processed and stored and used  later you are not going to run out of fuel  

in the next couple of hours or days if that was  the case then humans would never have survived  

whenever we were without food for a day then  we would just kind of wither down and lay down  

and die and we wouldn't have the energy to go  out and catch more food the only reason that we  

have this idea of eating and getting energy and  feeling better in this moment is that we have  

trained a behavior into our system we've become  carb dependent and in a sense we've created  

a drug habit we've created because any time that  you eat something and it changes how you feel  

it's kind of a drug it's a form of stimulation and  if we train the body into a rhythm that becomes a  

habit now we have a drug habit of course it's not  like a heroin habit or anything but it's still  

a drug habit and that is why we believe that we  have to top off our energy stores every couple  

hours that's not the case now getting back  to the question of the video is it safe to  

exercise when you're fasting well it's going to  depend alright it depends on the type of exercise  

you're going to do it's going to depend on the  duration of the exercise are you gonna know for  

seconds or minutes or hours the duration of the  fast how long have you fasted and how long do you  

plan to continue fasting and also very important  how have you trained your metabolism is your body  

fully fat adapted does it know how to use fat  for fuel primarily or is it still carb dependent  

now let's come back to that question of where  does the energy come from and let's look at a few  

different scenarios first scenario you're planning  to do some aerobic exercise that's a low intensity  

exercise you can breathe deep normal breaths  you don't have to huff and puff but those deep  

breaths provide enough oxygen to provide you with  energy let's say that you didn't have breakfast  

so you've only gone 12 to 16 hours without  food now first case you are fat adapted that  

means that you've trained your body into using  fat for energy and you're going to use body fat  

and glycerin for fuel so body fat the fatty  portion of that tissue is going to provide 95  

or so of all the fuel you need and you're going  to need a little bit of glucose for the brain  

and your body is going to convert glycerin into  glucose for the brain glycerin is part of a  

triglyceride that's just how your body stores  fat and because you are fat adapted you're not  

really going to shock your body you're not going  to shake up anything it's just going to continue  

burning fat the way it normally does so you can go  forever pretty much i know there's no such thing  

as forever but until you get a blister or until  you need to sleep or until you run out of body fat  

you can keep doing this and not really stressing  your body it's a little different if you're carb  

dependent if you haven't trained your body to use  fat primarily now even at low levels you will use  

some carbohydrate you'll use a good  amount of body fat still but you will use  

some glycogen and because you have some glycogen  and because it's low intensity you can go a  

really long time but not as long as this scenario  because after 12 to 16 hours your glycogen stores  

are running pretty low and you're using up  some of the glycogen during the exercise and  

when you run out that's not a good thing now  you're going to feel really bad but your body  

is going to break down protein to try to come up  with some glucose when you run out of glycogen  

if you're fat adapted you could use glycerin for  glucose but if you're not then you're going to  

resort to breaking down protein and now you're  going to have some muscle wasting as a result  

next scenario you decide to do some more intense  exercise some anaerobic training that means  

you're going to push it until you start huffing  and puffing because normal breath or deep breaths  

can't keep up so what this means is even if you're  fat adapted you will need to use some carbohydrate  

anything above that aerobic threshold is  going to have to be supplied by glycogen  

but because you're so good at burning fat that  fat is still going to be the predominant portion  

of your energy supply but you will need to break  down some glycogen you will have plenty of energy  

because if you've had this lifestyle for a few  months and you're fat adapted and you've done  

some exercise your body has learned to build  up normal glycogen stores even if you're on  

a low carb or a keto diet and that means if you  decide to do some high intensity interval training  

then it's not going to be a problem your  body is going to know exactly what to do  

it's going to use fat it's going to use glycogen  and as long as you don't go on forever then it's  

not going to be an issue now what if you're not  fat adapted then you're going to be burning more  

glycogen than body fat and again these ratios are  approximate all i'm saying is that if you're fat  

adapted you're going to tend to use more body fat  than glycogen if you're carb dependent then it's  

vice versa but it's always going to depend on the  intensity of the exercise the more intense it is  

the more glycogen you're going to have to use  and also if you're carb dependent if you've  

trained your body to expect carbohydrate every few  hours and you've gone 12 to 16 hours without food  

now your glycogen is gonna run pretty low so if  you go exercising you're gonna run out of glycogen  

much much sooner and as a result you're gonna  feel really really weak you're gonna feel bad  

and you're going to conclude that you  have to eat carbohydrate in order to do  

anaerobic training and this is one of these  myths out there that you can't do intense  

exercise if you don't eat a bunch of carbs  well that's only true if you're not adapted  

to the alternative what about lifting weights  can you do that when you're fasting if you're  

fat adapted no problem you use primarily body  fat for you most of your energy but any time that  

you do something heavy you push yourself you do  a heavy set and your muscles start burning that  

burning is lactic acid which means that you broke  down some glycogen and again that's not a problem  

because if you've done this for several months  you're going to have plenty of glycogen to  

start with even on a keto diet here's the  thing that you want to keep in mind though  

is weight lifting does break down muscle right  you can break down muscle in a bad way if you're  

starved and your body is trying to make glucose  but in a good way that's kind of the purpose  

of weight lifting is that you're stressing  the muscles you're creating some micro tears  

and then afterwards your body repairs the muscle  and it's stronger than it used to be so by  

stressing the muscle it gets stronger but in order  for you to be able to repair it you need human  

growth hormone and that's why the body makes extra  growth hormone when you're fasting and when you're  

stressing the body but you also have to remember  to replenish the protein after the workout so  

if you had fasted for 16 hours and you go to a  workout and you create all these positive things  

but you don't eat let's say you go another 48  hours without food that's not a good thing because  

your body is going to try to repair these muscles  but it's not going to have the resources to do it  

so you're going to be in a deficit and the  body's going to try to borrow and scramble  

which is not ideal what if you're carb dependent  well the first several pieces here are going to be  

exactly the same but just like with the anaerobic  exercise you're going to run out of glycogen much  

faster you're going to feel much weaker you're  going to feel lousy and you're going to conclude  

that it's a bad idea to lift weights unless  you eat carbohydrate now let's go back to the  

aerobic scenario but let's say that you've gone  much longer you've gone at least three days maybe  

five or seven days it doesn't really matter  because now you're in a steady state you're  

fully adapted and things are just going along so  if you're fat adapted then it's the same thing  

as if you had gone 12 to 16 hours because you're  going to be burning body fat and glycerin and you  

can go as long as you have body fat to burn if you  started out as carb dependent though it's going to  

be very different because in 72 hours you have  burned through your glycogen and your body has  

no choice but to become fat adapted you're not  going to be as stable and feeling as good as  

if you've done it for a long time but your  body has no choice it's going to burn fat  

the difference though is that you're going to  be feeling lousy with any form of exercise why  

because it doesn't matter if you exercise or not  you're going to feel lousy after three days of  

fasting if you're carb dependent your body is just  not used to it it's having a hard enough time just  

coping with with staying alive while not eating  it's not dangerous you're just not going to feel  

good because you're in a transition phase and  if you add exercise to it that's just going  

to make matters worse what about anaerobic  what about intense exercise can you do that  

if you've gone 72 hours or more if you're  fat adapted then you're going to be using  

still body fat more than glycogen but you're not  going to have the full stores of glycogen because  

you're gone 72 hours or more without food so  you're starting off with less glycogen there's  

less resources in the body overall than if you  had eaten a ketogenic diet all along so can you do  

a hit exercise under those circumstances i would  say yes but i would use common sense i would  

make sure i take it maybe a little bit easier  or at least that you do it very very brief make  

sure that you just do a few seconds at a time and  that the whole workout only lasts a few minutes  

could you do something longer like an iron  man well you would probably survive it but i  

wouldn't recommend it because an iron man is very  very demanding it's high intensity it's anaerobic  

it lasts for hours and hours and hours so it's a  huge demand you're going to be breaking down your  

body you're going to be using up all the resources  it has and if your resources are not fully topped  

off then i just don't think it'd be a great idea  you probably wouldn't perform all that well you'd  

probably make it through but it wouldn't be a very  productive or necessarily a healthy thing to do  

if you're not fat adapted but you've gone 72  hours now you're becoming fat adapted but again  

you have almost no glycogen you're going to feel  absolutely lousy and i would not recommend that  

you do any anaerobic training if you're in that  phase if you go on three days and you're becoming  

fat adapted then your body is having a hard enough  time as it is what about weight lifting can you  

lift weights after three days of fasting if you're  fat adapted your energy is going to come primarily  

from body fat you're going to use glycogen for  the extra hard stuff when your muscles are burning  

that's lactic acid from breaking down glycogen but  you start off with less glycogen so i wouldn't go  

too hard or too long even though it's not going  to be a big problem here's the main key like we  

said before the purpose of heavy weight lifting  is to stress the muscles so they break down  

so they can rebuild and get stronger and you could  do that after three days of fasting as long as you  

don't overdo it but you have to make sure that you  eat something afterwards or don't do it because  

if you've gone 72 hours without you're in  autophagy your body is trying really hard  

to conserve protein and if you just break down  more protein it's going to put a tremendous strain  

you're not going to be able to repair properly  and that whole weight workout was really just  

destructive and if you're not fat adapted then in  72 hours you're becoming fat adapted you're in the  

process you have almost no glycogen left over so  if you work out with weight lifting you're going  

to break down even more muscle you're going to  break it down from tearing fibers from the workout  

you're going to break down even more muscle  from trying to make glucose for the anaerobic  

strain and you're going to feel really really  terrible so simply i would say don't do it  

you have to remember that it is safe but you  have to understand what's happening in the body  

if you've just been fasting 12 to 24 hours no  problem if you're doing longer fasts then it's  

extra important you understand what's going  on you go easy and you use some common sense  

watch lots of videos from this channel so you  start understanding how the body works and then  

put that together and don't be stupid if  you enjoyed this video you really need to  

take a look at that one next thank you so  much for watching i'll see you next time