I weight the same as I did 10 years ago. And if I measure my waist it is the same as it was. 10 years ago, I always bought size 32" jeans. They fit perfectly.
Same manufacturer, if I buy jeans today, I get size 30. If I try on size 32, they are too big in the waist. I know I am not a 30 waist…in real measurement anyways.