How much do you lose in 8 weeks by eating 1000 kal per day?

Probably about ten lbs?

1,000kcal a day would cause a weight loss of about 1lb a week, but you will be using ebergy in exercise as well, which will create a larger deficit.

And you will lose water weight at the start. It also depends on metabvolism, age, gender etc.

Hope I helped you? :)