Can Marijuana show up months later if you burn fat?

I heard that if you exercise or burn any of the fat that you had when you smoked marijuana some time in your future, even a year or two later, that you will release a small amount of trace marijuana in your system that will be detected by the test. It won't get you high, but you will test positive like normal even if you aren't high a few weeks after. Anyone know know more about this. I did some like once and I would hate to test positive months after when I don't even smoke the stuff. Supposedly you can if you burn fat. I know otherwise it wouldn't normally be detectable after about 3 weeks at most, but I'm not talking about that.

Thanks.