To me it's really not about weight it's about an overall look for both males or females.
If the male start looking too lean / skinny and is not eating I will pull him out of rotation either temporarily or permanently.
Keep in mind that males don't need to get around the same female more than once a month for 2 days.
And at a 1000 grams there is nothing to worry about.
A little trick during breeding season keep you male in the smallest tub possible when not breeding, it helps with feeding.