system
Given the following post, respond as if you're commenting on Reddit:
human
Having "water weight" is just another term for being properly hydrated. People at the gym that wear insulated jackets on the treadmill to lose it are idiots that don't understand what dehydration is or why it's a bad thing. CMV.

Every once in a while I see someone jogging on the treadmill wearing a heavy insulated jacket. The purpose of these jackets is to make you sweat more, to lose so-called water weight. For most cases this seems like a horrible idea that is just going to lead to dehydration. 

It seems like they heard the term water weight existed, then vowed to get rid of it because their goal is to lose as much weight as possible. What makes it worse is that these people weigh themselves beforehand, then again afterward, then congratulate themselves for that weight loss. They may actively try to avoid staying hydrated.

As a former boy scout, this stuff freaks me out. During hikes we were always encouraged to stay well hydrated. Dehydration and heat stroke can be dangerous, and your body operates better in general when properly hydrated.

The main exception here is if the person is a professional boxer, or otherwise competes in something that has strict weight limits where it's beneficial to be as close to the upper limit as possible. They know what they're doing and have no intention of staying in that state after their competition is over. I suppose this may be one reason it caught on with some people - people saw athletes doing it, and blindly copied it without understanding why. 

My girlfriend mentioned that in high school she was taught that you have to work out to the point where you're sweating before you start burning fat, so she thinks some of these people may be trying to "game the system". 

In short, my views:

* Water weight = being hydrated, therefore it is a bad idea to try to lose it.
* The goal of wearing a jacket on a treadmill is to make you sweat more for the purpose of losing water weight.
* People that try to lose water weight don't understand dehydration, or value what they see on the scale more than actual health.
* It's totally fine and common practice for professional athletes to dehydrate themselves slightly to be able to compete in their weight-class.


**EDIT: Thank you, everyone. I've gained some information that I hadn't considered before that puts some things into a new context, mainly that there are some valid reasons for doing so and that "water weight" is a real thing for some people and is separate from being properly hydrated.**
gpt
I can't speak for everyone's individual motivation, but wearing sweatpants or a heavy jacket while working out *does* burn extra calories.  It actually requires energy to sweat, so while yes, you're not gaining anything by losing the water weight itself, you **are** actually burning a few more calories doing the actual sweating.  So there is actually a real benefit to it.  

Obviously it's important to stay hydrated, but as long as you do that, you'll burn a few extra calories in the insulated jacket instead of the tanktop.