I gained 2kg in over 2 hours?

I weigh myself a lot and today I weighed my self before showering and after I showered I had fried rice with sausages and an hour later I weighed my self again but I gained 2kg?
I only ate ONE stick of celery after I had fried rice but my weight went from 80.7 kg to 83.4kg?
P. s I know I'm fat af so I'm trying to lose weight before I turn obese (for my height I'm just over weight)
I gained 2kg in over 2 hours?
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