Post Workout Weight Question

This is a good question.
I don't have the answer, but I have a guess...
I'd bet that the rehydration process just can not take place in real time. So yes, when you are done with your workout, you are down on weight, even if you have been hydrating properly.
Perhaps that's why about 6 hours later, you are caught back up to your 'normal' weight.

It is physically impossible to replenish what you put out during the activity.  Think of hydrating and taking in calories as slowing the bleeding, not closing up the wound.  Typically for longer activities (or ones in extreme temperature or humidty levels) you will lose somewhere in the range of 1 - 5% of your body weight through water loss.  Over 3%-ish you start to affect your performance.

But you can gain weight if your digestion decides it has had enough and shuts down.  This typically happens when you have overloaded your stomach with simple carbs and not enough liquid to dillute them so that they can be absorbed.  This is the reason Gatorade is only about 6% carbs in the solution.  It is all your body can abosrb in a given timeframe.  When your stomach gets overloaded it will just sit there and collect more as it can't process it fast enough.  Usual end result of that??  Orange Gatorade puke on the side of the road or something else in the port-a-potty.

No you shouldn't weigh the same but it dependent on workout duration.

assuming you as naked when weighing yourself

if you weight 180lb prior to working out. and you done working out and weigh 177lb. now you have to do some conversions.. 1lb is 16oz roughly so 16*3 = 48oz..

48oz is your sweat rate for workout longer than 45 mins. I built a spreadsheet to help people with this a long time ago..

if you workout for 30 mins or less, weight shouldn't change.. this also depends on your fitness levels and other things

Rick is dead on and the "slow the bleeding not close the wound" analogy is an excellent one. My sweat rate is nearly 1.75 liters per hour in warm weather. There's just no way for my body to absorb that much fluid in that time frame.

I know we used to have to get weighed before and after every practice in soccer pre-season in August in Virginia. We were not allowed to be down a certain amount, or we had to stay in the training room and sip sports drinks until we were back up (no gulping, either). We were two-a-days and three-a-days, the later ones in 95+-degree heat and 90+ humidity.

So, yeah, you shouldn't lose too much. I'd say the 3% sounds about right.

mmmmm wrestling practice wasnt so kind, we'd weigh before and after. If you werent down 5lbs you were in for some running till you were.

sorry that this is more than 9 years old...

http://www.nata.org/statements/position/fluidreplacement.pdf

Keep in mind that if you're burning 800 calories per hour and eating 300 per hour, that's a net loss of 500 calories per hour.  A pound of fat is about 3500 calories and a pound of carbs is about 1800.  So you'll lose a pound through exercise every 3.5 to 7 hours on top of whatever fluid loss you have even if ingesting 300 calories per hour.  (Which shows why 20 minutes of cardio 3x a week at the gym does almost nothing for weight loss.)