The FastDay Forum

It was fast day this Thursday, zero calories, my last meal around 5 PM Wednesday.

I started running around 2 PM, ran as fast as I could 5 km, rested for a while and ran back slowly. Totally about an hour of running, about 10 km.

Well, it was quite awful, not at all like when I run early in the morning of a fast day. Difficult to get up to decent speed and keep it there.

I felt better after taking a cold shower for 8 minutes, and have felt just fine the rest of the day. A lot better than before my run, no feelings of hunger or being tired.

The idea was to run on empty tank, forcing my body to burn fat instead of carbs.

I can stand the discomfort, no problem, but is it a good idea to to train like this on a fast day, am I burning fat like I intended, or am I wasting muscle mass? I get all kind of contradictory indications when I google about it.

It will be interesting to say what the scale says tomorrow about weight and fat percent.

Hi:

With fasting, very hard exercise will be harder than moderate, consistent exercise. If you would have run at a moderate pace, you probably would not have had the bad 'after effects'. The time of day is important, too. If you exercise in the morning you will have more blood sugar left in your body than if you exercise at night (without eating). If you 'graze' throughout the fasting day, you will have less problem with your exercise (and less fat burn). Sorry for the non-technical terms, but the idea is right.

As for fat burning, probably the same either way. Fat is easier for the body to convert to energy than muscle and is the (actually) third place it goes for energy - unless you are on a very low carb diet. Studies are starting to show intermittent fasting tends to burn more fat than a reduced calorie diet.

Finally, don't expect one day to confirm/deny a trend.

I'd be interested to know how it works out for you. I myself have added running intervals the morning after a fast day (before breakfast) with the same goal of fat burning vs carb.

There must be some optimal duration for fat burning. But at which point does it exceed the optimum and become muscle wasting, I wonder?

I don't believe that muscle tissue will be broken down for fuel under normal running of an hour or three - fat will be used but the rate of conversion is slower than glycogen so performance is reduced, like most people experience at the end of a marathon. What I do worry about is supplying enough glucose & protein within an hour of the exercise session to repair damaged muscle tissue and the replace some glycogen stores, and thus enable training/exercise the next day. I reckon that I lost some lean tissue after a couple of extreme sessions whilst I was still losing weight, nowadays I will go out on a cup of coffee but replace a proportion of what I calculate (or the GPS calculates) I have burned during the session by drinking chocolate milk/coconut milk or similar upon my return.
Before races I now carbo-load like in the old days, just to make sure what few muscles remain are full of potential energy!

How do you do it? I once went to the supermarket on a fast day and nearly collapsed on the way back. It's only two KM, although my bags were heavy and it was very hot but heat never messes with me...

Ok my exercise is on a much smaller scale but I walk 5/6 miles on each of my 3 fastdays with no problems whatsoever in fact this acts as a suppressant for me because I can't eat anything at all for quite a few hours amazing, so of course I rarely miss one and it keeps me occupied for a couple of hours. Good Luck Sue

That is still good exercise Sue, and it works really well as fat burning matches walking pace better than running, especially running hard which demands glucose/glycogen (and causes more tissue damage). I walked over 10 miles down the canal on Tuesday, at 16:35 min/mile pace, with no ill effects and it passed nearly 3 hours without thinking about food. I have always been able to walk on empty, but would counsel against running hard - fat burning is not quick enough, you need some glycogen to support it at fast pace.
TML - does your thyroid problem have an influence here? Would you normally have no problem with your shopping trip?

Edit - spelling!

I tried a zumba class in the early evening of a fasting day, having not eaten since the evening before and had zero energy, it was a complete waste of time. I'm also a runner and haven't tried running on a fast day yet - the zumba experience put me off, although if I went out in the morning, I'm sure I'd cope a lot better. Not sure how I'd feel for the rest of the day though...

Well, I went from 76 kg yesterday to 74.1 kg today Fat percent from 18.3 to 18.1 %, waist down 1 cm. Not that such anecdotical numbers are very relevant I guess.

I'm a bit concerned my weight drops faster than my fat percent in general. I love long distance running and my rowing machine, I also do a few pushups or some simple muscle exercises 3-4 times a week.

I suspect I'm slightly on the wrong path if I want to become ripped and fairly muscular. Unfortunately endurance cardio is what I enjoy, but if I continue like this I'll probably end up just looking skinny.

I probably should be going to the gym and start with some high intensity muscle training. Too bad gyms are such ugly and depressing places, compared to the dose of absolute beauty you get when you go for a run in Stockholm.

If I don't want to start going to the gym and lift weights two or three times a week, and I don't want to eat anything on my fast days since I want the maximum health benefits, when should I run, and how?

Perhaps it's best I simply train and eat the way I'm comfortable with until I get downn to the body fat level I'm aiming for. If I look too skinny by then so be it, that's a new problem to handle on it's own instead of trying too hard to do two things at once.

Hi Michael H,
who has read my blogs in the past (I have been absent for a while now), knows I do long distances. I started 5:2 in March and was preparing at that time a 100km run. My trainings are usually long runs 3 or more hrs and I do them quite often on an empty stomach with the same idea of teaching my bosy to get the energy from fat rather than glycogen. I never had problems bot running on fast days than normal days, being them empty or full stomach. Just yesterday i went for a hard run (only 11km but dìfast pace) at 2pm with 33 degrees outside and I was fine on my fast day and without having had breakfast or anything else since the night before. I guess it is just a matter of habit. As Creakypete said it is very important that you eat within an hour after finishing your training, but I suppose you know already this. I usually weight myself before and after training, but it is just to know how much fluids I need to intake to replenish what I lost sweating and the weights I usually take daily for me are important on a long term basis. After my 100km run and even after my 24hrs race later (171km done) in July I kept loosing weight the days afterwards the races, meaning the body keeps burning after such hard efforts.
Well I hope my experience helps a bit.
Just keep training normally and eat accordingly to the amount of exercise you do. Weight will come down and I don't think you need the gym. Running keeps my muscles fit and toned and for sure I don't need the gym, even because it is known that runners are skinny and not bulky.
Ciao,
J

Yes from what I read, running with an empty stomach will certainly burn fat, but forget about burning fat or muscle for a minute or two and think what it will do to the body. It is not at all a good idea to run on an empty stomach, especially if you haven’t eaten for a long time. You should at least have eggs, oatmeal, fruit, or any juice before running or exercising.

ahen for me running on an empty stomach is essential if I don't want to throw up during a run (sorry TMI)

Take a look at Breaking Muscle, it's an online magazine with lots of ideas and debate about how best to do things. If you read around, you can work out a way to attain your goals.

http://breakingmuscle.com/

You don't have to train in a gym, in the UK we now have lots of parks where functional fitness camps are run. Even if you like to run on your own, you can do bodyweight exercises all round a circuit. So dips on a bench, burpees, pullup off a branch. Even GHD exercises can be done with a park bench.

It's not all or nothing, fitness has evolved from just gym or run.

I always train fasted now as I'm adapted. It's best to know how best you function, I can't eat before training so even if I wasn't fasting those days, I'd still not be eating. Sian has just posted why! Each to his own.

Oh, and I'm certainly not losing muscle fasting...functional, high-intensity exercise means I'm now a totally different shape!

Ahen23: Disagree entirely - which bits of the body will suffer if your stomach is empty? Best scenario is empty stomach and full glycogen reserves, well hydrated.