Weight loss during a slow run

gqma0

Hi.

I'm preparing my 3rd marathon and I still have a lot to learn but here's a question for you guys.

I'm trying to assess how much water I'm losing during a long run to compensate over a long run.

I'm training with a Garmin HR training plan and I did a test over a slow run for 50mn in z2. I weighed myself before and about 20mn after I stopped without consuming anything between and I lost 900g (~2lbs). I'm not sure if I really lost that much in dehydration. I don't sweat that much in slow run and don't breathe heavily. I'm not sure if I lost that much fat.

The last marathon, I believe I didn't drink enough and my quads seized in the last 6miles. It could have been many factors but dehydration could be the major factor.

The question more about how much water / fat ratio I'm losing. This is also relevant to the zone I train in so I don't think there's a generic formula.

Cheers.
Gaetan

Krusty_Clown

It's probably safe to assume the weight discrepancy is 99% water. Just generalizing here, but over a 50 minute run (depending on your weight/speed etc)., you probably burn around 800-900 calories, which wouldn't equate to anything like 900g of body solids/fat. Probably best to drink plenty of water afterwards (while avoiding hyponatremia, and your body will get rid of any excess water.

TFBubendorfer

Krusty_Clown wrote: »

Just generalizing here, but over a 50 minute run (depending on your weight/speed etc)., you probably burn around 800-900 calories

I'd say more like half that amount. As far as I know 1 mile of running burns roughly 100 calories.

ger664

For every gram of glycogen (energy you burn) stored it requires 3-4 grams of water for storage. When you burn off glycogen in a run the body dont need the excess water so it no it gets rid of it.

gqma0

Krusty_Clown wrote: »

It's probably safe to assume the weight discrepancy is 99% water. Just generalizing here, but over a 50 minute run (depending on your weight/speed etc)., you probably burn around 800-900 calories, which wouldn't equate to anything like 900g of body solids/fat. Probably best to drink plenty of water afterwards (while avoiding hyponatremia, and your body will get rid of any excess water.

tbh, I don't know how accurate the Garmin calculates the calories but I didn't burn that amount.

http://connect.garmin.com/activity/433947082

I guess that it was more water than fat as the body burns fat much slower. It's just I don't feel I sweat much at that pace and I'm not out of breathe.

On my 1st marathon, I drank regularly but just a mouthful to keep my hydrated and I may have taken too much as I stopped twice to the toilets. On the 2nd marathon, I didn't drink that much and only drank at thirst but mile 20, I got cramps in the quads and I had to stop. The last 6 miles were agonizing as I was running at a speed where my quads wouldn't seize again and it became a run/walk. I'm not blaming entirely the lack of water as I hadn't trained much for the 2nd one but I still did my long runs.

I drank 1l of water after the run anyway

Krusty_Clown

gqma0 wrote: »

tbh, I don't know how accurate the Garmin calculates the calories but I didn't burn that amount.

http://connect.garmin.com/activity/433947082

Yep, sorry, as per TB's post, I way over-estimated the number of calories. I usually work off a rough figure of around 100 calories per mile. Anyway, this further widens the gap between your exercise and likelihood of burning 2 pounds fat. Little doubt that this is largely water.

Avoiding cramps isn't necessarily about drinking water. In fact, there is still much debate about the cause of cramps, and dehydration is just one of the proposed causes. Others include: low salt, low potassium, etc. etc..

RayCun

Krusty_Clown wrote: »

Avoiding cramps isn't necessarily about drinking water. In fact, there is still much debate about the cause of cramps, and dehydration is just one of the proposed causes. Others include: low salt, low potassium, etc. etc..

can't remember where I saw it, but there's also a suggestion that it is often caused by insufficient tapering

huskerdu

I agree with Krusty and TTR. There is no need to overthink it.

As has been said, running 1 mile burns off approx. 100 calories. Your body will take this from its glycogen store.
If it runs out of glycogen over the course of the day, it will use some fat. It is highly unlikely that you actually burned off any fat at all
in a 50 minute run. It might have contributed to you burning off a bit of fat over the course of the day, if you had an overall calorie deficit. but not in the 50 minutes.

Also, 1 lb of fat = 3500 calories, so your 50 minute run, if you ran 4/5 miles was the equivalent of a fraction of a lb of fat.

gqma0

huskerdu wrote: »

I agree with Krusty and TTR. There is no need to overthink it.

As has been said, running 1 mile burns off approx. 100 calories. Your body will take this from its glycogen store.
If it runs out of glycogen over the course of the day, it will use some fat. It is highly unlikely that you actually burned off any fat at all
in a 50 minute run. It might have contributed to you burning off a bit of fat over the course of the day, if you had an overall calorie deficit. but not in the 50 minutes.

Also, 1 lb of fat = 3500 calories, so your 50 minute run, if you ran 4/5 miles was the equivalent of a fraction of a lb of fat.

Great, so, I can assume it was mostly water loss and I should compensate to roughly the same amount of water during long runs. I will have to assess and see over the long runs in the next few weeks.

Thanks

MacSwifty

Keeping hydrated all the time will also help - do not just up your intake during and after runs - make it a habit of sipping small quantities regularily throughout the day

Enduro

You're more likely to overdrink than drink too little. Google "waterlogged" by Tim Noakes to see some of the more modern research on sports hydration. Don't drink if you're not thirsty. The best advice is probably to stop over-analysing and just get out and run more. Running is simple... just do it. Unless you're running for multiple hours in hot weather its unlikely that you need to worry about drinking whilst your training.

gqma0

MacSwifty wrote: »

Keeping hydrated all the time will also help - do not just up your intake during and after runs - make it a habit of sipping small quantities regularily throughout the day

I drink at least 2l. daily along with a balanced diet of fruit/veg ;-)

huskerdu

Enduro wrote: »

You're more likely to overdrink than drink too little. Google "waterlogged" by Tim Noakes to see some of the more modern research on sports hydration. Don't drink if you're not thirsty. The best advice is probably to stop over-analysing and just get out and run more. Running is simple... just do it. Unless you're running for multiple hours in hot weather its unlikely that you need to worry about drinking whilst your training.

Great advice. Just drink water when you thirsty. 50 minutes running in Irish weather will not dehydrate you. At the moment, its more likely to leave you with trench foot.

gqma0

Enduro wrote: »

You're more likely to overdrink than drink too little. Google "waterlogged" by Tim Noakes to see some of the more modern research on sports hydration. Don't drink if you're not thirsty. The best advice is probably to stop over-analysing and just get out and run more. Running is simple... just do it. Unless you're running for multiple hours in hot weather its unlikely that you need to worry about drinking whilst your training.

I've read many articles and I get confused which is why I'm asking advices. I'm unsure what to take and what to leave.

http://running.about.com/od/nutritionandhydration/a/hydration101.htm

http://www.runnersworld.com/drinks-hydration/drink?page=single

The test of weighing myself before and after surprised me about how much water I lose and one clear answer is that I definitely lose water even in easy/recovery run which I will need to compensate over the long runs. I usually drink a pint about 30mn before any training session just to keep hydrated and I drink a lot after. Urine color is my indicator. On a long run (120 to 180mn), I take 1l but this may not be sufficient enough since this is what I lose in 1h. but at the same time, in past long runs, I've had water sloshing in the stomach which indicates I drank enough (And I don't gush it down in one go) so it seems the body may not process the water at the same rate as if you were running 1h or 3h but I guess sodium is a factor to retain the water.

Again, this is my 3rd marathon and I'm trying to judge when/how much should I take. I'm not a big fan of sports drink as they make me sick but what I do on long distance runs is that I mix water/lucozade and use gels as well. Nutrition and hydration is something important. I'm relying on your experience.

plodder

I'd agree with the other advice on not worrying about it. You are most unlikely to get dehydrated in our ciimate (except during unusually hot weather). But, I would say, if you like to drink water, then that's fine too. Your body will get rid of the excess. You really have to be chronically drinking to excess to worry about Hyponatremia in my opinion. Runners who get hyponatremia mostly get it during marathons, where they drink only water without replacing lost sodium. If water is sloshing around your stomach, you are drinking too much, too close to your training sessions.

Enduro

gqma0 wrote: »

I've read many articles and I get confused which is why I'm asking advices. I'm unsure what to take and what to leave.

http://running.about.com/od/nutritionandhydration/a/hydration101.htm

http://www.runnersworld.com/drinks-hydration/drink?page=single

The test of weighing myself before and after surprised me about how much water I lose and one clear answer is that I definitely lose water even in easy/recovery run which I will need to compensate over the long runs. I usually drink a pint about 30mn before any training session just to keep hydrated and I drink a lot after. Urine color is my indicator. On a long run (120 to 180mn), I take 1l but this may not be sufficient enough since this is what I lose in 1h. but at the same time, in past long runs, I've had water sloshing in the stomach which indicates I drank enough (And I don't gush it down in one go) so it seems the body may not process the water at the same rate as if you were running 1h or 3h but I guess sodium is a factor to retain the water.

Again, this is my 3rd marathon and I'm trying to judge when/how much should I take. I'm not a big fan of sports drink as they make me sick but what I do on long distance runs is that I mix water/lucozade and use gels as well. Nutrition and hydration is something important. I'm relying on your experience.

It sounds to me that you're totally overanalysing the situation and tying yourself up in knots as a result. My advice, again, is to stop doing that and just run. If you feel thirsty then drink. If you don't feel thirsty then don't drink. Stop weighing yourself and stop analysing the colour of your urine. Paralysis by analysis is coming on! We've evolved over millenia to deal with hydration naturally.

To give an example of my own routine.... I rarely drink before I head out training, for the simple reason that I'm rarely thirsty. If I am thirsty I'll drink a small glass of water. I almost never drink when I'm on a training run. About 4 times last year I needed to grab a drink on a training run, but those were during the summer heatwave, and the runs were all at least 4 hours+.

gqma0

Enduro wrote: »

It sounds to me that you're totally overanalysing the situation and tying yourself up in knots as a result. My advice, again, is to stop doing that and just run. If you feel thirsty then drink. If you don't feel thirsty then don't drink. Stop weighing yourself and stop analysing the colour of your urine. Paralysis by analysis is coming on! We've evolved over millenia to deal with hydration naturally.

To give an example of my own routine.... I rarely drink before I head out training, for the simple reason that I'm rarely thirsty. If I am thirsty I'll drink a small glass of water. I almost never drink when I'm on a training run. About 4 times last year I needed to grab a drink on a training run, but those were during the summer heatwave, and the runs were all at least 4 hours+.

Don't get me wrong. I'm not overanalysing here, neither do I check/test the color of my urine and I've done the test only once recently simply to see how much water I'd lose and how to compensate for. I'm no beginner here and I don't take water with me to run for 1h or more but I do if I go for long runs as I feel thirsty.

The whole point of a forum is to share information and experiences. I don't run to compete, although I do since joining the club. I simply do it because I enjoy it but there are questions that I don't have answers and come from experience that I'm learning from others and the hard way most of the time.

Anyway, my original query is answered. thank you for your answer

gqma0

Actually. Re-reading through my comments, I think you're right Enduro. I'm overanalysing here. My 2nd marathon wasn't the most enjoyable experience and I don't want the 3rd and 4th to be the same. The thing is I followed advices from the guys who have done many marathons. Drink at all water station a mouthful and that didn't work out for me, so I'll simply grab a bottle a drink at will when I feel like it.

gqma0

Looking back at this thread, I thought I'd post a comment about it.

I've now run many marathons and was always struggling with long distance and I knew I was dehydrating despite the fact I was drinking enough even too much. Following a sweat test, it turns out I'm a heavy sweater and lose a lot of sodium. Nothing I can do about it (DNA). I've been doing triathlons in the last 3 years along with other multi sports activities (Quest, Duathlons, Aquathons, etc..). On Sunday, I did my first IM 70.3 in Dun Laoghaire and took my salt tablets (I don't think I can mention the name on the forum) but there's only 1 guy from Kilkenny who's the official tester and provider

Anyway, to cut a long story short, I haven't suffered dizziness, cramps, disorientation or any other symptoms I used to over long distance anymore and I swear by these tablets. They are better than any eletrolytes you find on the market. First IM 70.3 in Dun Laoghaire in 6h30mn.

It took a while to figure out but I now know hydration is a science and we're not all the same.

Singer

Interesting stuff! Thanks for showing back up here

walshb

2 lbs over 50 minutes slow run is very normal. 50 minutes sitting on a couch could see you drop 50-100 gs...

OP, I think you may be overthinking it all. It’s just weight loss from time and effort..all thus searching via in-depth biology and chemistry as regards water and calories and fat etc...

Just drink small amounts during your marathon. Be fairly hydrated, but not too much, before you start. 400-500 mls per hour seems a “correct” amount of water.

ger664

Your body stores ~3g of water with each 1g of muscle glycogen. Once you burn off that 1g the body doesn't require that water but makes use of it by cooling you down from the heat generated in burning that energy in the form of perspiration.