I have been running about a mile sometimes a mile and a half with a jacket or sweater on after a hour and half workout. and was wondering if wearing a jacket/sweater could actually improve reducing fat levels faster than running longer or would it be unhealthy from sweating so much in 80+ weather?
running while wearing a sweater/jacket will only rise your body temperature, so you'll sweat a lot to cooldown your body, that's only water loss, not fat
No, you're only sweating out more water.
edit: beat me to it
There is no way I would ever do cardio in the summer with a sweater on. Like these guys already said, it'll only make you sweat more and if it's warm out that can actually be dangerous though I doubt it would be after a mile.
I wouldn't run after a workout. I couldn't, even.
The people who "started" this trend/myth were people in boxing or any other martial art where a boxer sweated out as much as possible while limiting water intake to "make weight" for a fight. They would of course rehydrate as soon as it was expedient to do so and would "regain" the weight they "lost".
Using this method to lose weight would lead to severe dehydration and weakening.
If you really, really wanted to you could use a weighed vest.
Or run up some stairs.
Or run up some stairs with a weighed vest.
And the cramping.
Let us not forget those.
Ahhh, to wake up with the feeling of a knife stuck through your calves....