Exercising on an empty stomach?

I've read different articles about this, some saying a small pre workout snack is good, fuels you, etc. And others saying to work out on an empty stomach so your body doesn't have so much fuel to work from that it doesn't start using fat as fuel. (Or along those lines anyway, you know what I mean!)

And I should say I don't mean working out having not eaten for 2 days, or you're so hungry you're in pain! I workout when I get up in the morning, and say if I get up at 7am and haven't eaten since 7.30pm the previous night, is it ok to work out on an empty stomach? I don't find that I get fatigued or lightheaded after/during my workout.. And I always make sure to refuel straight after!

Just wondering what works for you and has ether option helped/hindered your fat loss?
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Replies

  • No_Finish_Line
    No_Finish_Line Posts: 3,661 Member
    i've read things saying fasted cardio will help you burn more fat.

    if it does, its marginal at best.

    not worth being dizzy and what not.

    I'd say do whatever allows you to do the most work as thats going make the best work out and probably greatest calorie burn.
  • Cherimoose
    Cherimoose Posts: 5,208 Member
    Depends what kind of "workout". 30 minutes or less of moderate-intensity cardio should be fine on an empty stomach. For anything more vigorous, longer, or involving strength training, it's good to fuel up prior. It doesn't take much - a few ounces of juice or a piece of fruit, for example. Mostly carbs / sugar, since that's what your body lacks in the morning.

    By the way, i know of no *long term* studies showing that exercising on an empty stomach burns more fat. Most studies i've seen lasted about 1 day.
  • M_miller0507
    M_miller0507 Posts: 16 Member
    Do what works for you. The differences will be minimal if they exist at all.

    Personally, I can't work out if I've eaten recently. I work out first thing in the morning on an empty stomach. This includes half-marathons. If I try to eat before I run or lift I feel awful.

    If you work out better with a little something ahead of time, then eat. If you feel better without anything, then don't. Do what you have to do to be successful.
  • micheleb15
    micheleb15 Posts: 1,418 Member
    I workout at 6am and have a banana before. I used to not eat anything for cardio, but the banana definitely helps with my strength training. Gives me just a little more energy.
  • fishgutzy
    fishgutzy Posts: 2,807 Member
    Personally, I can do 90 to 110 laps ( 4 to 5km) on an empty stomach. But if I want to do more than that I have to eat a good breakfast 2 hours before swimming. That is why I save the long swims for the weekend.
    Early morning 5AM swim is 90 laps.

    If I swim right after work, I will sometimes grab a Detour protein bar before I change to go to the Y.

    Earlier on I would get dizzy from low blood sugar if I didn't eat enough before a second swim on a Saturday. But not anymore.

    Everyone is different. Your body will tell you what works and what doesn't.
  • TavistockToad
    TavistockToad Posts: 35,719 Member
    Some people can do it, some people can't.... I can't! But then I dont workout first thing in the morning, so it doesn't matter!
  • CarsonRuns
    CarsonRuns Posts: 3,039 Member
    I run every morning on an empty stomach without any issues. This past Sunday, that "workout" was a 2 hour, 45 minute run. I had plenty of stored fuel in glycogen and fat.
  • No_Finish_Line
    No_Finish_Line Posts: 3,661 Member
    depleting you glyocgen stores by lifting before cardio is supposed to produce the same effect btw
  • Escape_Artist
    Escape_Artist Posts: 1,155 Member
    I lift and run fasted all the time. Always have my last meal at 9PM, workout at 5AM and I usually only eat my first meal at 1PM

    Some people can workout fasted and others can't. Whatever works for you.
  • This will matter or duration and intensity of your training. While I don't discredit the research saying you'll lose more fat, personally the trade off is not worth it for me. I train hard and when I don't eat before I fall flat on my face. I can't run as far, lift as much, sustain as high of a heart rate, and I lose the will to keep pushing. IMO the marginal benefits of training fasted don't even come close to its effect on my abilities. No way is training half as intense, half as hard, or lifting half as much going to worth it.

    That said, if you are doing low intensity steady state cardio for a short duration I see no reason to not train fasted. Every time I'm at the gym I see people doing cardio at a snails pace playing with their phones and I wonder why the even do it. IMO push yourself so training fasted isn't even an option.
  • JaxDemon
    JaxDemon Posts: 403 Member
    Unfueled cardio has been proven to help burn more fat.
  • SoDamnHungry
    SoDamnHungry Posts: 6,998 Member
    Depends on the person.
  • AngelsFan91106
    AngelsFan91106 Posts: 111 Member
    You have to see what works for you. It looks like a lot of people here workout on an empty stomach. Personally, I NEED food, especially carbs, before I lift or do cardio. If I don't, I don't perform as well. And I've gotten downright dizzy on occasion.
  • Echoing "whatever works for you" but also adding that there is no scientific backing that says exercising on an empty stomach will necessarily force your body to look to fat stores for fuel.

    So yeah, do what works for you. :) If you're seeing results, you're doing it right.
  • If you go to bed hydrated and you ate the right amount the day before, fasted AM cardio is great. If you're dehydrated it can be awful. It'll ruin the rest of your day. Best of luck!
  • owieprone
    owieprone Posts: 217 Member
    i can't do it, i can barely walk down the stairs on an empty stomach any more :( i used to be able to get to lunchtime without eating. I have MDDS so being hungry is dangerous for me, which suits me immeasurably as i love eating lol can't think of a better excuse for grazing throughout the day on fruit and veg :D

    there are lots of studies on it however, but i've not read them, just the news articles so couldn't say for sure, i think like everything else it depends on the person how much impact it has. If you want to try it, i'd ease in to it, no point making yourself ill or getting injured just to lose that extra pound a month, if you put it back on unable to exercise with a broken ankle or concussion ;)
  • xxhieixx
    xxhieixx Posts: 89 Member
    If I did it in the mornings when I woke up it would be great. I usually go out for a walk then come back and eat. However, my zumba class is at 7 pm and I try to eat at 5 so I'm not starving. If I don't eat before zumba I'm definitely STARVING afterwards and I hate feeling like that. The only time I've ever done that is if I know I'm going out to eat or ordering out afterwards. I usually go home and make dinner so after class I have a good hour and a half - 2 hours before dinner is done.
    I don't know what your schedule is like so if you prefer to work out on an empty stomach then go for it. I hate it but everyone is different :)
  • EmmaNilsson77
    EmmaNilsson77 Posts: 38 Member
    An interesting take on why to do it, but only occasionally; http://www.runnersworld.com/running-tips/running-e
    Personally, I do it because I have to get up and out the door before I'm fully awake, or I won't go.
  • Look at it this way.....If you have/had kids would you let them play a soccer game on an empty stomach?

    The answer is NO! It is dangerous to work out on an empty stomach. Your blood sugar levels go into shock as well as your muscles will suffer. You should NOT eat a huge meal and then work out but healthy snacking about 15minutes before hand is good.

    The theory is to not deplete your body but build muscle/strength when you work out. Can't do that if you are being carted off in an ambulance because you fainted.
  • digbybebe
    digbybebe Posts: 25 Member
    My main meal is in the pm so I usually run on empty...anything from short runs to 15km or more. For me, water is the key...I drink lots and always have but if for any reason I drink less than normal one day, my workout suffers the following day. Even if I drink plenty just before exercising. If I have to exercise after eating I have to wait at least 2 hours or I feel quite churney and not great at all.
  • shawnakrebs
    shawnakrebs Posts: 50 Member
    I always work out on an empty stomach, not even coffee. I have jogged, Tae Bo, dance, and I am currently doing Insanity. When I have eaten in the past I get stomach cramps, so over the years I just started doing any workouts in the AM before getting anything in me but water (and small amounts). I did Tough Mudder on the protein snacks they offered and did just fine. Do what works best for you. Some people need food, especially in the AM since you have gone all night with nothing to eat and your blood sugars are low.
  • I am not a scientist and have not looked at any research regarding the fasted vs nonfasted cardio debate.

    With that disclaimer out of the way I can say that I have done both for extended periods of time due to work schedule. I used to workout in the early AM fasted, cuz I liked to eat breakfast at work. Then my schedule changed and it became more conveniant to workout after work, and since I wasn't going to fast all day cuz I like to eat:) I would workout after eating my afternoon snack. Just the way the timing worked out. I noticed no improved loss of BF% one way or the other. As long as I got in my workouts and stuck to my cal goal I lost weight at the same pace both ways.
  • lyndabyh
    lyndabyh Posts: 187 Member
    If you go to bed hydrated and you ate the right amount the day before, fasted AM cardio is great. If you're dehydrated it can be awful. It'll ruin the rest of your day. Best of luck!


    This^ I work out first thing in morning on an empty stomach and feel fine, unless dehydrated then workout is terrible and generally end up with a low grade headache all day. Can tell if my water intake was low the day before as soon as I start.
  • tmm_0127
    tmm_0127 Posts: 545 Member
    Do whatever works for you.

    I personally can't exercise on a completely empty stomach, I feel too weak and get dizzy. So I either eat and wait an hour or two (depends on what I eat / how heavy it is) or I eat a light snack before I get busy.
  • FrnkLft
    FrnkLft Posts: 1,821 Member
    I just read the best thing... "diet for weight loss, exercise for fitness". If you follow that mantra, you'll be fine. Eat back your burned calories.

    And the answer is no, it doesn't make a difference, and eat before your exercise so you can put in a good workout and keep your body from breaking down your muscle for energy instead.
  • ATT949
    ATT949 Posts: 1,245 Member
    I've read different articles about this, some saying a small pre workout snack is good, fuels you, etc. And others saying to work out on an empty stomach so your body doesn't have so much fuel to work from that it doesn't start using fat as fuel. (Or along those lines anyway, you know what I mean!)

    And I should say I don't mean working out having not eaten for 2 days, or you're so hungry you're in pain! I workout when I get up in the morning, and say if I get up at 7am and haven't eaten since 7.30pm the previous night, is it ok to work out on an empty stomach? I don't find that I get fatigued or lightheaded after/during my workout.. And I always make sure to refuel straight after!

    Just wondering what works for you and has ether option helped/hindered your fat loss?


    Given a subject who is untrained but normally nourished, if they exercise at 70% VO2 max, they will exhaust liver and muscle glycogen.

    What I just wrote means that you have to work very, very hard to deplete all of your glycogen unless you're running about 20 + miles.

    Pick up a copy of "The Lore of Running" by Dr Time Noakes and read through chapter 2, esp around page 98 (going from memory).

    While we navel gaze about minute amounts of nutrients, we are doing that from a body that has spent 5,000,000 years figuring out how to survive. We wouldn't have lasted this long if we needed to stock up on food before we went out to do what is, in the big scheme of things, small amounts of exercise.

    Having said that, some folks don't do well without something extra in the tank (that's who the sabertooth would snack on!). Much of that is psychological (not surprising since most of us are here we had an eating disorders at some time) but losing weight and running can kick your butt (I recently dropped about 5 pounds in 10 days and things got pretty tough at times).

    Your body will always use some percentage of fat as fuel. It varies with a huge number of factors but your body will switch between fuel sources in real time. I have a trace that shows how my CHO/fat percentages sitting vs moving about the house. Sitting I was burning 60% fat ---- as soon as I stood up and walked up the stairs, fat % plummeted and CHO levels took off. When I got to the second floor of the house, the percentages reverted.


    Here are some links to some images:

    cbeinfo.net/running/images/hr_vs_fatpercentage_running_20130125.jpg
    cbeinfo.net/running/images/hr_vs_fatpercentage_sitting_20130213.jpg
    cbeinfo.net/running/images/hr_vs_fatpercentage_walking_20130127.jpg

    Those images are from the .FIT file generated by a Garmin 610 with R-R recording activated (the top of the line Polar and Sunnto HRM's have that option) The file was opened and analyzed using FirstBeat Athlete software.

    Some comments:
    1 - there is no medical evidence to substantiate a claim that it is "dangerous to workout on an empty stomach". During endurance training (long distance running), it is a common tactic to train without taking on fuel. The goal is to force the body to use fat as a fuel (because even skinny people have many pounds of visceral fat) instead of burning glycogen (which most of us here on MFP have well under half a pound of glycogen in our bodies)

    2 - the amount of water we ingest prior to or during exercise has, for practical purposes, no impact on an exercise of short duration, regardless of temperature. Of course, that's an anathema to "drink, drink, drink" crowd but understand that just as much as there is zero medical basis that we need "8 glasses a day"*, medical research clearly indicates that all we need to do is "drink to thirst" and we will be able to do things like run marathons in high temperatures.**

    How is that possible?
    The older remains of our species were discovered in the Olduvai Gorge in the Rift Valley in Africa (http://en.wikipedia.org/wiki/Olduvai_Gorge) . We survived because we adapted our bodies to be able to chase down prey until it died of heat exhaustion. Yes, a gazelle can outrun human in a short distance race but, because humans have such incredible heat dispersing capabilities, our ancestors would track the animal, wait until it faltered, and then finish it off.
    Our species simply would not have survived if we needed to "pre-drink"


    *Drinking lotsa water has benefits for some folks when losing weight - it helps loosen you up if you're constipated; it's really hard to eat if you've got a water bottle in your hand; and it can fool your stomach because you feel full. Other than that, nada thing.

    Refer to the research by Dr. Valtin and even Snopes has dealt with topic:

    http://www.ncbi.nlm.nih.gov/pubmed/12376390
    http://www.dartmouth.edu/~news/releases/2002/aug/080802.html
    http://ajpregu.physiology.org/content/283/5/R993.full


    **Ref "The Lore of Running" and also "Waterlogged" a newer book by Dr Noakes in which he explains how water and thermoregulation function during exercise and he also details how the "need to drink" water and energy drinks coincides very, very clearly with the discovery and marketing of Gatorade.
  • BlueBombers
    BlueBombers Posts: 4,064 Member
    Honestly, it really depends on each person.

    I get up at 5 a.m. to workout most mornings and food is the last thing on my mind that early in the morning. I eat after my workout.
  • I work out at 5 am so I generally don't eat before. I used to grab a banana on the way out the door but found I really didn't need it as long as a refuel after I get home!
  • LBNOakland
    LBNOakland Posts: 379 Member
    I Love fasted cardio! Hate having anything on my stomache for that!

    Lifting is a different animal. I get up at 4:45 and walk 3 miles with a friend. As soon as I get home, I go to the gym 2x a week. 1 night a week, I go to the gym after work to work with a trainer. Although, I probably haven't eaten since lunch, it isn't as long a time period as sleeping. I noticed my workouts were easier in the evening. I really don't have time to eat in the A.M though. I have to take a medicine 1 hour before eating so I take it before my walk. I have found that if my dinner the night before is high in protein, my morning workouts go better even if I haven't had a chance to eat anything. So I make sure I eat high protein the night before when I know I am going to the gym the next day.