The short answer…NO! fast day is 500 calories (600 for men) or 25% of your TDEE whichever is the lower. It’s not a good idea to ‘eat back’ exercise calories on a fast day as the idea is to make your body get rid of stored fat. It won’t do this successfully if you increase the calories you eat.

Reaching my height to the maximum level? Wait whut? If you mean to say exercise has many other benefits besides calorie burning, I completely agree 😉

Hi All,
I’m no expert here, but I was listening to a cycling podcast about 18 months ago, and they were talking about the paleo diet for cyclists. The expert (Joe Friel) talked about how the body adapts to burning fat instead of carbohydrates when living on a low (or no) carb diet. He also tried to dispel the tradition of carbo loading leading up to an event with the fact that fat is energy dense, and you don’t really need much in the way of fat stores in your body to be able to exercise for a very long time.
This previously was always a concern of mind, when thinking about paleo, or sugar free, or whatever other regime friends or family talked about. But with theories about how much energy dense fat stores I’m walking around with, and that I could train my body to not require lots of carbs before and during exercise, I thought I’d give the 5:2 diet a go. You see, I cycle to work twice a week, and being a fair weather rider, I change the days I ride quite often. It’s 32km each way, and I treat it like a training ride, not a sunday ride. We’re talking trying to keep the pulse above 140-150 (75% max HR) for the entire 75 minute ride. I’ve found that fasting has seemed to make zero impact on my performance. I really thought it would on fast days, where I have no breakfast, a coffee at 10, no lunch, a coffee at 15:00, and only eat at dinner time.
I would’ve thought the morning ride would use anything I had stored, and with no solid food all day, the 75 minute ride home I would bonk (cycling term for zero energy).
Well, it hasn’t proven to be the case so far, I’m really surprised, and impressed at the ability that the human body has to be able to perform with what ever resources it has to use…

Peter.

I’ve been on the 5:2 for just over 18 months now and I started introducing hard exercise in to fasting days after about 3 months. I’m a cyclist and as long as I keep the work out to under 2 hours (ideally 1.5 hours or less) I actually find I have better performance on fasting days. Around 10%.

I normally save all my calories for the evening meal and just eat maybe 50-100 with milk in coffee and tea during the day. However on an exercise day I will eat just a little before a serious work out. Typically a small piece of fruit, just to keep me going.

I tend to find exercise kills my hunger any way. The only thing I would say with High intensity training is to adjust your zones to take account of your lower HR on a fasting day. Typical HR for me on a fasting day is 35-38bpm and 43-48 on a normal day. I set my Max at 178 on eat days and 170 on fasting days to take account of this. Otherwise the world starts to look a bit pink when flat out. 😉

If you find it hard doing fasting and exercise stick to what I call the safe foods Soups and salad, where you can really eat rather a lot and fill up without taking on lots of cals.

Reading this is really interesting. It was only my second fast day today, so I’m a newbie. I’ve been running twice today (I usually run 3-4 times a week, generally with a rest day between), and found it no problem at all. In fact, I got a PB on my second run of the day! I had some fruit for ‘lunch’ after my first run, and am now about to have my main meal. I’m just starting to feel a touch hungry, but have been fine all day. I almost feel as though running on empty has been easier.

Hi leigh and welcome:

The question is ‘What is your goal?’

Do you want to lose weight or build muscle?

5:2 is simple – 500/600 calories or less on your two diet days each week.

Many people successfully exercise on their diet days. If you want to exercise on yours, just eat 500/600 calories of carbs and protein. But you get no ‘extra’ calories for exercising, as exercise is included in your TDEE.

If that does not work for you, exercise on non diet days and eat what you want.

This might help: http://thefastdiet.co.uk/forums/topic/the-basics-for-newbies-your-questions-answered/

Good Luck!

Just re-iterating for newbies, in case they haven’t read this whole discussion. Although, long-term there should be no problem doing whatever exercise you want for however long you want on a fastday and suffering no energy lag (you might actually find, like me and many others, you actually perform better on ’empty’), if you can’t face it as a newbie then don’t beat yourself up about it.

Get used to the fasting first, then look at introducing additional exercise on fastdays. If you can’t do that without upping your calories on your fastday (very slightly) to begin with then don’t beat yourself up about doing that either. Just be sure to reduce back down once you are accustomed to it.

And for those who cannot/ will not be doing any additional exercise alongside 5:2 – don’t feel like you’re a second class 5:2er or you’re somehow doing it wrong. You DO NOT necessarily need to do any additional exercise (beyond what you’ve always done/ not done) with 5:2 in order to gain health benefits or lose weight.

Many moons later… I spoke to my Dr about this and he said yes, absolutely. It’s 25% of calories, so if by exercising you’ve burned 600 calories, you can increase caloric intake the that day by 25% of calories burned exercising. It’s also helpful to know your basal metabolic rate to know what 25% of your base metabolism is to know with more accuracy what 25% of your daily calories burned are to set your fasting goal. I’ve been consuming up to 750 on the days I fast where I burn 600 calories in a workout. I count every single calorie though – tracked through an app. I also know my BMR is 2200-2300 cals daily. So that, plus 500-600 cals burned in an hour of HIIT, X 25% puts me safely at a max of 750 cals.