5:2 with running

This topic contains 22 replies, has 13 voices, and was last updated by  Sarcina1991 4 weeks, 1 day ago.

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  • I have been run/walking for about 2 years and have done 5 half marathons. I love it and do not want to give it up. Is it possible to do IF and keep running? I am not training for anything now, so it seemed like a good time to try. I did my second fast day yesterday and also ran 2 miles. Felt tired, but not terrible. I need to lose about 20lbs and really want to give this a try. I’m hoping there are others like me. Any advice is appreciated.

    Short answer is yes. With practice you should be able to get up to about 85% or so of your FPT. I don’t run but cycle. You wont set any PB but there is no reason you cant fast and run, just sit on about 80-85% of the pace you would normally sit on. Lots of top athletes now train in a ketogenic state.

    Take it easy to start with, it will take at least a month before your liver starts to become well adapted to processing stored fats. Been doing it for about 9 months now and the last month Ive noticed its a lot easier.

    That is great to hear. I plan on only doing longer runs on Saturdays when I won’t be fasting the day of, day before or day after. Can’t avoid it on other days. I will experiment with running days and see what works best. Glad to hear it gets easier.

    I am fasting and running too and actually now I pick for running only fasting days. If your stomach is empty and body is not processing any food, it has more energy for moving activity. It’s much better.

    I have no problem combining running with fasting. I don’t run long on my fasting days (max about 16km) and use these days as practise for non-carb energy burning. I save my long runs (20+km) for days that I am not fasting.

    I have been running marathons (and one ultra) for years and cannot feel any negative difference in my marathon training since starting fasting.

    The important thing is to make sure you are well hydrated on your fasting days.

    Thank you for your replies! It’s been about 3 weeks now and it is getting a little easier. I’ve found that I can run the morning of a FD, but evening is very difficult. The morning after a FD is also very difficult. I will avoid these if I’m training with friends, because I don’t want to hold them back, but on my own I don’t mind a hard run sometimes. Generally I’m planning my runs around FDs. It’s working so far.

    Great to hear others doing it too! Anyone training for anything specific? I’ll be starting training next week for the Savannah Half Marathon in Savannah, GA, USA.

    I’m just starting trying the 16:8 today – I’ve done the 5:2 for a couple of weeks but it feels hard to fit into my sked with my kids or socially. Skipping breakfast & abstaining until lunch feels more manageable so far and allows me to feel “normal” with my sked. Guess I’ll see how it works when/if I lose any weight! I did do a workout this morning so can really feel my hunger and insulin dropping & will try running tomorrow…will be interesting to see how that translates as well. Wish me luck! 🙂

    Good luck, paleofast! I can tell you that it definitely gets easier with time. I have been doing 5:2 and training for my half for about 10 weeks. I don’t really notice much difference now when I run on fast days. I am still avoiding fasting near my long runs. I have lost 11 lbs and that alone makes running easier! I have noticed the loss has slowed down some the last couple of weeks. My miles are getting higher and I think I am eating more on NFD. Which is fine with me. I don’t mind losing slowly as long as I’m feeling well and running well.

    Anyone else running and fasting? Want to compare notes and keep each other motivated?

    Let us know how 16:8 goes. Without intending it my routine has already evolved into 14:10, so it wouldn’t take much of a stretch to move to 16:8

    Thx! It feels more “manageable” to feel the hunger but know that I can eat in a few hours – I suppose if I stop eating earlier at night then my 14 hours comes up faster, but what I’d rather do is stretch it to noon or 1pm regardless to try to gain the most benefits. I’m definitely hungrier than normal since I worked out, but that kind of feels good (in a sick way) too! It’s only Day 1 of this regime, but I’m already liking it more than 5:2…we’ll see!

    BTW, coffee with sweetener & no cream is just vile…;-)

    Ah, misunderstood. I assumed you were doing 16:8 on your none fasting days. I think I’ll try both – I have always found it easy to skip breakfast and I normally eat very early evening. I have just completed two consecutive fasting days so we’ll see how the gym goes tomorrow morning without breakfast.

    Ah gotcha – didn’t even think about combining 16:8 with 5:2…I’ll see how a week (5 days) of 16:8 alone goes then possibly try to combine it with 5:2. The appeal of the 16 for me was how it fits better into my schedule rather than trying to plan my social life (or kid time) around when I can and can’t eat/go out, etc. These forums are super helpful – keep the support coming! 🙂

    Hello all.

    I’m new to 5:2 and also new to running. Looks like I’ve found the right forum! Just curious, do you have any ‘program’ recommendations for a beginner? I’ve done the Couch to Five K program before, but wanted to explore other options.

    Also, is anyone weight training along with the running? I used to be an avid lifter but don’t want to do TOO much all at the same time.

    Thank you!

    Welcome moecho. I hit the weights at least once a week, combined with the rowing machine. Running was my main activity, 6 days a week, total 40 miles, but my back and knees are not as keen as they were so I mix it up and try for a variety of activities.

    Thanks Penguin! Appreciate the feedback.

    so glad to found this thread.. the read was interesting. i am 3 weeks into 5:2 i am trialling it on my down running time. after reading your comment SP13 feeling better about doing marathon/ultra training on the 5:2.. you must of found the balance between the 2. as i have run on an empty stomach and really struggled to get the distance, and with summer coming distance runs are a struggle in the heat anyway. sunday is my big run day so i should be ok as monday & thursday or FD
    happy running 🙂

    Hello! I am starting week 3 of IF. I didn’t run on fasting days my first week, and last week ran on each of my fasting days, and also on non-fasting days.
    I’m finding that my endurance is fine at a moderate pace, and even better than it was for runs in the 4-5 mile range, but in general, I don’t feel like I have my same power when doing interval training or sprints, either on fasting or non-fasting days. Does it just take that much time for my body to adapt?
    And this may be related or off-topic here, but I see reference to training in a ketogenic state here and in the book. Does it matter if I go into a ketogenic state for even a short period of time, ie, are there any longer lasting effects from training in a ketogenic state? Can I truly be in a ketogenic state if I exercise on the morning I begin my fast? I do typically go through a hunger stage during my run during the first mile on FD, but it subsides.

    Hi J-ray. I’ve also been doing this for about 3 weeks and have been running on my fast days. I used to run in the morning for about 35 minutes but I get really hungry afterwards and that makes the FD much harder. Now I run and cycle in the evening before I have the luxury of a small evening dinner. I have a theory that if I run in a fasting state, then I’m using fat as a fuel, at least in part. The next part of my theory is that endurance training is easier because my body is used to using fat as fuel after glycogen and blood glucose have been used up.
    I can’t run as quickly on a FD and I’m not sure I’d want to try anything like interval or hill work. But having an easy running day while fasting doesn’t seem to present any problems to me now.

    I used to run six days a week but with advancing age (now 72) , a damaged spine and dodgy knees I stopped and for the last couple of years I have worked out in the gym. Since starting 5:2 I have lost a lot of weight. I was a heavy runner. Out of curiosity during my last gym session I tried the treadmill. Back and knees were fine with it but after half a mile I had to stop – no stamina. That surprised me, I regularly walk 6 miles. I may be thinner and the muscle strength is fine but clearly when it comes to running I have to start from scratch and build it up again.

    Hey runners!

    Doing half marathons on 5:2 fasting definitely is possible, you just need to listen to your body a bit more.

    I started with IF in beginning of April this year and ran two half marathons and one 10km race since I have started. All in all, I did not see any negative effects, in fact, I decreased my half marathon time from 1:41:17 just before starting IF to 1:40:03 about one month after starting to 1:38:55 (finally! 😀 ) two weeks ago. Also my 10km time improved from 45:20 last year to 44:30 this year in May.

    My intention is not weight loss, so I am not so strict with myself on fast days. I usually keep exercise to a minimum on fast days, but if I happen to run on fast days, I eat a banana before and a small meal afterwards, roughly balancing the calories I ran off (usually a plate of fruits with 300 – 400 kcal).

    For me, easy runs up to 15 km work fine on fast days. I do not do intervall trainings or long jogs on fast days.

    I think you have to be careful to get enough overall calories when extensively training for a half marathon in order to not risk injuries from incomplete recovery.

    Good luck!

    Hi I have been doing the 5:2 for 1 month successfully. I was 73kg and have lost 5kg so far. The problem is I have 43% body fat (acc to my scales). I also have MS and have had a problem with my foot which is now feeling 99% better. I have always wanted to run and am new to it. I am going for my first run tomorrow. Are there any tips to help reduce my body fat or schedules I could follow for running? Thanks

    Don’t trust scales that tell you a body fat percentage! With 73 kg, 43% of body fat for sure is incorrect!
    If it is important for you to know your body composition, invest in a bioimpedance analysis. At least in Austria, you can do this at some nutrition specialists, doctors or fitness centers. However, you can also follow your weight/fat loss by measuring for example your waist size. Also, do not put too much pressure on you just for numbers. You will see and feel, whether you lose fat (in case this is even necessary – I do not know your gender or size, but 73 kg does not seem overweight for me) or just muscles (which also happens on intermittent fasting if you do not get enough calories, protein and fat on eat-days).

    About running – if you are completely new to running, try to alternate between running and walking. Just 20 minutes is enough for the beginning. There are tons of plans, this is just an example: https://www.popsugar.com/fitness/8-Week-Plan-Go-From-Walking-Running-3252493
    Of course, if you are in general fit or you feel like running longer than just a few minutes – go for it. However, I would not start to run more than 25 – 30 minutes for the beginning, because your tendons and ligaments have to adjust, not only your muscles and endurance. This is REALLY important: Even if you feel that you can run 1.5 hours immediately, if your legs are not used to it, you can easily develop knee pain. Pain from running is NOT normal. Whenever you feel pain (usually knees are the weakest point) it probably results from increasing duration/speed to fast.
    Of course, having sore muscles after your first run is totally normal and fine. Just do not overdo it 🙂

    I am a triathlete. Female-54. Yes I battle hormones. 🙂 I have been doing this for the most part for 2 months. (fell off the wagon on my vacation) and it is not my imagination. Running after a fast day is horrible! On days I don’t eat, as long as I do so the day before, training in the morning is no problem. My fast days are Tuesday and Thursday. I teach spin classes 2 days a week, ride my bike outside 2 days a week, which includes a long ride of 40-60 miles on the weekend. I run 3-4 days a week, which includes a longish run of 10+ miles on the weekends. I swim 2-3 days a week. I train 6-7 days a week, and obviously twice a day on many. I have lost next to no weight, and the quality of my workouts the days after fasting suffer. I am not considered over weight by normal standards at all, but I am heavier than I want to be. I eat for the most part healthy, but thought this might be a great way to drop the stubborn (7) pounds. I’m ready to give up. Any suggestions?

    Hey Trikim!

    Here are my suggestions what you could try, based on how I handle IF at the moment:
    I stopped doing complete fast days, as I love eating dinner after a long day and hate going to bed hungry. Obviously I could probably overcome this by just getting used to it but it’s not worth it for me at the moment. So I have two “half” fast days per week, usually Monday (rest day) and Wedensday (only easy runs): I try do not take in calories for at least 12 hours. So I have dinner around 10pm, then have a coffee with some spelt milk around 10 am (~50 kcal). If I am super hungry and cannot concentrate anymore, I eat something really small like a banana or an apple or some cottage cheese with raw vegetables around noon ( 100 – 200 kcal). For dinner, I have some boiled potatoes (500 g – 350 – 400 kcal) with a tea spoon of butter or some cottage cheese (100 kcal). Potatoes are great in my eyes because they are filling and you have a proper amount to eat without having too many calories. I end up with around 800 kcal on “fast” days, 1000 if I go for a run.
    As I said, I only do easy runs on fast days and I do eat a banana or something afterwards. I once tried intervalls and it was horrible and for sure not efficient.
    When I do intervalls AFTER a fast day, I eat something small or drink a fruit juice before.
    I try to do long runs before breakfast, independently of fast days.

    About not losing weight: After all and independent of all other benefits that IF might have, weight loss is still about caloric deficit. If you haven’t yet, you could try to monitor your calorie intake over a whole week for one or two weeks. I did this when I startet IF and realized that on eat days I eat enough to balance the calorie deficit of fast days (which is fine because I want to maintain my weight). This is another benefit of eating something on the evening even on fast days – I am not starving the day afterwards and don’t eat that much.

    Hope I could help and wish you good luck!

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