fasting and gym?!?!

This topic contains 20 replies, has 7 voices, and was last updated by  Josh v 8 years, 10 months ago.

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  • hello all

    i am new to this as of next week – i want to lost approx 20lbs in 3 months for my holiday in July

    i am going to fast on Mondays and Thursdays

    i am a regular gym-goer though (3-4 times p/w, weekdays only) and concerned that gymming on my fast days will make me nearly pass out with the lack of energy/normal calorie consumption!!

    does anyone else find this or is it manageable??

    many thanks!! 🙂 x

    Hi,
    I go to the gym 3 mornings a week, the day after a FD. I do approx 75mins cardio, followed by 30mins resistance work and a swim. I don’t have any problems working out, but I’m always very hungry afterwards so I don’t fast on the same day as a rule. If you go early morning, you could try doing the same, but if you go after work and it is a FD, I suggest not eating until lunchtime and have something like an egg salad, and then have dinner afterwards. Might I suggest that you give yourself a chance to get used to fasting, which may mean less gym visits for a couple of weeks. The most important thing is drinking enough water on fast days, and if you are working out you’ll need to drink more than usual or you will feel faint.

    Good luck.

    thanks for the reply 🙂

    i can’t go early mornings because i start work very early – i go about 4pm

    i will definitely ease off for the first couple of weeks while i get a feel for it. after strenuous exercise i lose my appetite for some time straight after anyway, so this might work to my advantage.

    Hi, I’m just starting with my second go at this and I’m also a regular gym user. My advice would be not to train on a FD. The reason I say that is because your muscles need glucose in order to work and if you are fasting you will have relatively low levels of glucose in your blood stream. If you are working out and your muscles are demanding glucose that is not readily available, your metabolism will actually start to break down muscle fibre to convert to glucose to feed itself… in other words your muscles will turn cannibal and you will loose muscle mass as a result! Not good!

    ok that sounds mildly terrifying :-/

    The glycogen stored in your liver and muscles which is readily available and easily converted into glucose will be more than sufficient to prevent the likelihood of that happening with the length of fasting usually undertaken on 5:2. Endurance athletes such as marathon runners can experience muscle breakdown due to depletion of glycogen stores, but that is unlikely to occur after a session at the gym on or after a fast day.

    Thanks Amazon, but doesn’t the glycogen in your liver and muscles become depleted when you are fasting so that it’s insufficient to fuel a workout? Endurance athletes take a lot of care to ensure that they have sufficient stores of glycogen (pasta parties before the marathon for example) and consume a lot of glucose before and even during their events to prevent muscle breakdown (drinking lucozade for example) but if you are fasting wont you be effectively running on empty even before your workout?

    Hi therose, I didn’t change my exercise regimen for the first 18months on 5:2 (ie: not very much exercise) but for the past year I’ve been doing my main exercise sessions of the week on fastdays as a matter of course. I swam pretty regularly throughout the week and did a couple of other classes but my BIG energy sapping workouts were all on Fastdays. On Monday I’d go all day with no calorie intake (water only) and then do 45 minutes of Body Combat at the gym, followed by 20laps or so in the pool and a SwimFit session before going home for my 500kcal meal. No problem at all. On Wednesdays I would do BoxFit for an hour at lunchtime. Again – no calories throughout the day and Wednesdays are my late work nights so I’d get home and have my 500 at about 7:30-8pm. No problem.

    I wouldn’t recommend pushing yourself early on in the 5:2 lifestyle. If you think you may need time to ‘bed in’ then take it and avoid fastday workouts until you’re used to the lifestyle. I’d say it took me a good few weeks to become a ‘fat burning beast’ as the paleo-fans would put it 😉

    Oh, Monty28 – I think that’s the point of 5:2 though isn’t it? It gets you to deplete your glycogen so that when you workout you don’t have that available and you switch to burning your fat reserves instead. You don’t want your muscles to suffer, so you don’t take the ‘deprivation’ to extremes (undereating your BMR more than 2-3 times a week) but as long as you’re not ACTUALLY starving, your body is going to go for your nice juicy fat stores before it starts eating muscle tissue. Plus you can always have a protein rich 500Kcal to help repair & build your muscles after your FD workout.

    I guess runners do carbs before a long run because they always have and their bodies would go into ‘shock’ if they ran out of their ‘normal’ fuel mid-run for no obvious reason. However, I don’t see why you wouldn’t be able to train your body to cope on fat reserves instead?? Maybe a resident nutritionist can educate me but I’m a fairly long-distance swimmer and I’ve never conked out in the middle of a 5K swim on a fastday.

    Endurance athletes don’t have any fat to burn and we do, which is why we are doing IF.
    Tracy has said more or less what I was going to say, so I’ll just agree ith her 🙂

    Hi Tracy 🙂 it would be great if you were right about the body using fat before muscle but I don’t think that is how it works. The first time I tried this diet I loved working out on my FDs because I actually felt more energetic than on eating days (weirdly) but the main reason I stopped the diet was because of this issue with training and fasting not being compatible. This time round I’m only going to train on eating days (I used to train everyday regardless). I’m really interested to hear yours and other people’s views on this subject because I love the 5:2 lifestyle and it definitely works for me but I don’t want to ruin my body composition doing it.

    My body composition is much improved. I’ve lost 64lbs of fat and my muscles are bigger and stronger. I am fitter, healthier and have more energy than ever before.

    This is fascinating!

    Tracyj, your comments make sense, but why are you starving if you eat below BMR more than two or three times a week?

    On 4:3 and ADF or you not doing exactly that? Surely athletes with very low or zero body fat have a problem with the body ‘eating’ muscle, but someone with 30%+ won’t have. Wouldn’t the body burn off all the fat before muscle?

    I work to TDEE at a target weight, not my ultimate target, an interim weight, but it means that I am working around my BMR calories for 4 or 5 days, doing a quarter of those calories on one or two days, and a full fast at least once a week.

    I thought starvation mode came in after weeks of continuous full fasts.

    Interesting Amazon – I eat nothing at all on a FD. I’ll have a skinny latte and a couple of cups of tea with semi-skimmed milk over the whole day (maybe 150kcal in total) but I don’t have my 600 allowance because I figure proper fasting is better than semi-fasting but maybe that idea is wrong. However, is it not the using of the glycogen from the muscles that actually IS muscle ‘breakdown’?

    Monty you make an interesting point regarding your concern for your body composition. I am sure that you are aware that building muscle involves working it to the point of causing small tears, and that when the healing process is complete it will be bigger and stronger. Glycogen stored in muscle is only used by muscle when other glucose is not available, and the rest of the body uses that which is stored in the liver.
    If using up its store of glycogen is what is meant by the term muscle breakdown, then there is no reason for concern as it is not in fact destroying or damaging muscle tissue, and will be replaced as soon as excess glucose becomes available. Any excess will be stored as fat, something we all know about. When doing IF and depleting glycogen stores the fat will be used until we refuel our bodies with food, which as Tracy so aptly put it, is the point of doing 5:2
    I hope that makes sense 🙂

    Proper fasting means a greater calorie deficit and therefore a slightly faster rate of weight loss, which is a good thing.
    My previous post regarding glycogen depletion on 5:2 was inaccurate as I was a little confused and should have checked the facts before posting.

    It does make sense! Thanks Amazon – I will get back to working out on FDs now 🙂

    Oh dear, Sorry my post threw up some confusion, just popped back in now – glad it all got resolved. All the best everyone 😉

    I’ve been carefully re-reading all of this.

    Fab advice and discussion from everyone, thank you.

    On reflection I’m going to continue gymming on fast days. I did it on Monday and felt fab – i just had a small banana an hour or so before for a bit of energy and left most of my calories for the protein-rich meal afterwards, and then was full till bedtime. Spot on and am repeating today. Especially if it means more likelihood of eating into your fat stores and be the optimum for fat-burning; this is obviously exactly want I want to happen.

    Thanks everyone for your input and good luck in your ongoing diets 🙂

    hi all, just wanted to share my experience. I started 5:2 about 10 months ago, had some success and then stopped when I went travelling in Europe for 10 weeks.

    I started 5.2 again in January this year and by that stage had been back at the gym for 3 months and was working out 4-5 times a week for 45-60 mins but had only shifted 1kg. I didn’t want to restart 5:2 earlier because I was worried I couldn’t fit it into the gym schedule. I am not an extreme gym goer by any means, a big session for me would be body attack followed by body pump and I only do that occasionally. But like a lot in this discussion I was worried I wouldn’t be able to perform at my best.

    Anyway, eventually I felt like I was used to exercising again and so re-started 5:2 in January. At the start I only exercised on non-fast days but after a while it became easier to just exercise when I could fit it in and so gym days ended up on fast days sometimes. At the start I really struggled and felt like I wasn’t putting in 100% by the end of the class, but I think it was more in my head than my body.

    Just this week I got to the end of a workout and didn’t even think about the fast day until I was on my way home and started thinking about what I needed to do to cook tea. I don’t think I perform ‘better/worse’ on fast/non-fast days as other people have said but I do find the gym distracts from the fasting because I don’t eat anything until the evening.

    Good luck everyone xoxo

    @mrsciv

    Couldn’t agree more – I am not an extreme gym-goer either; i do 3-4 times a week for an hour – about half hour cardio and half hour resistance/weights. I realistically burn about 500 calories per session so it by no means results in feeling ill or faint on a fast day. I could understand the risk of a lack of calories and energy for something like a marathon – but for the sake of an hour’s moderate to intensive exercise, if anything, I’m feeling like i have more energy and am lighter as I’m not full of food from lunch. To be honest this is probably psychological, like I’m on a roll and ‘hammering it’ – I’m sure there will be days when i struggle or feel hungry and can’t be bothered. But having a small banana for energy an hour or so before keeps off the hunger pang, and then i have a high protein meal afterwards.

    Gym days therefore may or may not fall on fast days, but I’m not going to worry if it does – in fact I’ve decided that it’s preferable to do so, as it will help burn more fat, as discussed above

    I’ve just came across this thread and was seeking reassurance ,
    I’m now back on the 5:2 but intend to do it on the 4:3 basis for a few months.
    When I last entertained the 5:2 diet I always made sure I didn’t attend the gym on a fast day . However today and my previous fast day I’ve been to the gym and completed a full body workout , I find it take your mind away from feeling the hunger but what I want to know how do you feel a month down the line on a gym session which was also a fast day ?

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