Whats wrong with my scales?

At saturday morning i i drunk a bottle of milk since i had a football match quite early.After finishing the match i went on scales showing me being 83 kgs.After that i ate a morning meal with2 bottles of milk and a donut with chocolate cream and after that i went on scales again BECause i've heard that after eating u are more weight and i was 81 kgs!a good justification?