Weight gain after workout

Yesterday I did some running/walking for 15 mins? I couldn’t go longer because my legs were a bit sore from doing that the other day and I didn’t wanna push too hard, and I also did 15mins HIIT exercises. Today my body is sore and I like to weight myself in the morning. When I did I weighed 1.5lbs more.

What I ate yesterday..

3 boiled eggs

Banana

I hate 2 finger fulls of granola (I looked at the back and saw it had a bunch of sugar so I put it back immediately)

For dinner I had Boston market.. I had white meat chicken, mashed potatoes, macaroni, as well as 5 of those bread things.

(Yes I did feel bad after the meal but I didn’t lay down I did some walking around.)

I normally don’t gain weight from eating like that rarely maybe .5lbs not a whole pound plus the .5oc, but stupid question short are there any other factors that could’ve caused it?