How long does fast weight loss last?

I am morbid obese and a little over a month ago I was 430 pounds and today I am 396! I exercise like crazy I try to do at least 2hrs a day. How long can I expect this fast weight loss before it slows down?

P.S. I know for 100% sure I am eating more calories then my food diary says because I don't have a food scale and I don't measure. I just eyeball it and guess.

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