Exercising whilst fasting?

Is it safe to exercise whilst on a 500cal fast? And if I do, should I add the calories I burnt on top of my eating calories?


  • cwolfman13
    cwolfman13 Posts: 41,826 Member
    I wouldn't....why are you eating 500 calories? You burn far more than that merely breathing.
  • cwolfman13
    cwolfman13 Posts: 41,826 Member
    Pagynwb wrote: »
    I'm only doing it twice a week as part of a fast. Its a diet called 5:2, you fast two days a week, and eat normally the other 5. - Why wouldn't you suggest it? Is it dangerous to be exerting oneself on such a small calorie intake?

    I guess it would depend on if you're doing 5:2 the way it's supposed to be done...which means you'd be eating plenty on non-fasting days.
  • DopeItUp
    DopeItUp Posts: 18,772 Member
    edited March 2016
    I'd probably recommend getting your workouts in on your normal eating days. But if you absolutely must train on your "fasting" days then I'd probably recommend at least a small amount of carbs pre-workout and some protein post-workout (or thereabouts). Even just a single serving of gatorade will help get your blood sugar up pre-workout, which can make all the difference in the world.
  • mkakids
    mkakids Posts: 1,913 Member
    Ive followed 5:2 in the past and exercised on fast days. It depends on the person. Some people feel fine....some dont. Its ok to do, as long as you feel ok.
  • Hell_Flower
    Hell_Flower Posts: 348 Member
    I do.

    I find that smashing a good cardio workout first thing in the morning actually helps the fast day. I don't feel hungry for a good 4 hours after working hard on spin bikes.

  • Froggymcconnell
    Froggymcconnell Posts: 92 Member
    I would suggest forgetting diets and make it a lifestyle changes. Diets are short term.
  • 6pkdreamer
    6pkdreamer Posts: 180 Member
    Ive been on 5 2 in the past and I had the same dilemma. Generally I concluded that adding calories for exercise is a good thing as you are rewarded 4 exercise. Better to be a fit fatty then a unfit skinny!
  • StealthHealth
    StealthHealth Posts: 2,417 Member
    I did 5:2 for a while (I now follow an Intermittent fasting protocol). I've used fasting during loss, maintainance and now a bulk cycle (muscle gain) and I've used some sort of fasting for years.

    I've continued with my exercise programs throughout, including my 600 (guys get 100 more) cal days without any significant loss of performance (I run and lift).

    Warning: I strongly recommend, for anyone employing a fasting protocol, that you continue to accurately count calories, primarily ensure that on your non-fasting days you are eating enough food (although counting on fast days is useful to ensure compliance)
  • sijomial
    sijomial Posts: 19,811 Member
    I did 5:2 but made sure I ate at maintenance on the the 5 normal eating days. Really think if you are going to follow 5:2 then try it as it's laid out rather than 2 days big deficit and 5 days small deficit.

    No you are not supposed to eat back exercise calories on the 2 fast days. On the 5 days you can either do TDEE method or the MFP eat back exercise calories method - personal preference.

    At first exercising on a fast day was hard but over time (weeks/months) I completely adapted so that cardio or strength training felt entirely normal.

    Would advise taking it gently at first and build up intensity steadily. Alternatively if fasted exercise doesn't feel good for you then use the 2 fast days as rest days and exercise hard on your 5 maintenance days when you are fully fuelled.
  • amusedmonkey
    amusedmonkey Posts: 10,330 Member
    edited March 2016
    It's perfectly safe. It may feel a little hard at first and you may feel lightheaded, but then you get used to it and it becomes normal. I do eat back 25% of my exercise on fast days because the general 500 calorie recommendation is basically just an easier rule to calculate and remember than the real value used in research which was 25% of TDEE.
  • abbietaylor1
    abbietaylor1 Posts: 31 Member
    I did 5:2 for a while and the advice I always received was YES you can exercise on fast days but NO you can't eat back the calories. I generally found walking was the best bet because it wasn't too strenuous but it took me out of the house to take my mind off eating :) Good luck!