different weights before and after workout?

gibsy

Can anyone explain why I always weigh in 1.5-2 lbs lighter after a workout than immediately before?

This happens consistently, but clearly I am not actually losing 2 pounds in a one hour aquafit class. I would think maybe I just sweated off water weight, but if I'm in the pool I'm not hot so I'm probably not sweating, right? That just seems like a big discrepancy to show up so fast.

MoreBean13

Its water weight. You are sweating in the pool, you just don't notice it because of the water.

gibsy

Maybe this is a stupid question, but why would you sweat if you aren't hot?

blamo87

Yes you sweat while you are in the pool. If you are using energy, your body is heating up and sweating naturally. You may feel cold from the water but you ARE sweating. So yes it's water weight.

gibsy

OK, cool. That makes sense.

My follow up question then is that if you can lose 2 pounds of water like that, then there is probably a 2,3,4 pound window where changes one way or the other don't necessarily indicate fat loss or gain, right? How can you be sure you really lost a couple pounds, or if there's just some other factor going on, like maybe you've had a good poop and aren't retaining water?

I ask mainly because I see people counting weight loss or gain in single pounds or even half pounds, but how can you know that's fat loss and not just some other random variable factor? People often beat themselves up over a one or two pound gain, but that could just as easily be something like water too, right? Is it totally pointless to take note of single pounds or should you just be looking at the broader trend over time?

Thanks guys, I'm new to this so I have a lot of very entry level questions.

MoreBean13

No that's a totally legit question- the way to minimize fluctuations based on water weight is to weigh yourself first thing in the AM, after you do your business. Still, you will see some water weight fluctuation due to muscle swelling, TOM for women and other hormonal changes and water retention from things like too much sodium, but it reduces those influences to a minimum. I weigh myself daily but don't count losses for a couple days, to try and rule out fluctuations, and I never count gains 'cause I know I'm eating at a deficit, lol. Daily weighing is too much of a mindf*ck for a lot of people though, so weighing once a week, first thing in the AM like I said before works very well for many people.

Many athletes weigh themselves before and after workouts to measure hydration. If you lost 2 lbs, then by the "A pint's a pound the world around" rule, you need to replace 32oz of fluid, in addition to the regular fluid you consume.

gibsy

Thank you, that's very helpful. I don't have a scale at home and usually weigh myself either at the gym, or at the doctor's office, both of which I usually go to mid-day. I have thought about getting a scale though, and the morning thing seems like a good idea. I'd be curious to weigh daily just to get a sense for what kind of range and influences come into the fluctuations. I've always been approaching it like there's no cause to worry within about a 3-4 lb zone, as long as the trend is settling up and down within that particular zone or declining in the long run.

Ok so I have one more question, more of a sciencey one I guess. When exactly does your body "burn off" the fat it uses? Right in the moment, or later? I assume it builds muscles slightly later, as a repair thing, right? But does the fat literally get used up and disappear in the moment it's being used, or is there some slower process?

Thanks again! Understanding exactly what my body is doing makes this all so much easier and more interesting!

MoreBean13

Thank you, that's very helpful. I don't have a scale at home and usually weigh myself either at the gym, or at the doctor's office, both of which I usually go to mid-day. I have thought about getting a scale though, and the morning thing seems like a good idea. I'd be curious to weigh daily just to get a sense for what kind of range and influences come into the fluctuations. I've always been approaching it like there's no cause to worry within about a 3-4 lb zone, as long as the trend is settling up and down within that particular zone or declining in the long run.

Ok so I have one more question, more of a sciencey one I guess. When exactly does your body "burn off" the fat it uses? Right in the moment, or later? I assume it builds muscles slightly later, as a repair thing, right? But does the fat literally get used up and disappear in the moment it's being used, or is there some slower process?

Thanks again! Understanding exactly what my body is doing makes this all so much easier and more interesting!

It's more long term- you create a deficit everyday, and your body has to release fat from fat cells to make up the difference. There's some minor adjustments you can make by exercise- if you weightlift and then do cardio for example, your body releases hormones as a response weightlifting that makes you burn more fat during the cardio- but most of the change will be over time as a response to a calorie deficit. As far as muscle- you're right. Muscle is built during rest, never during the workout. Its why rest time is so crucially important. Many people mistake muscle swelling for muscle growth- actual perceivable growth takes a long time and a lot of effort.