[checkyoursudo]

I am not sure I would rely on observations of gyms and beaches for whether people are healthier for fear of selection bias. Going to the beach and seeing mostly fit bathers is like going to the hospital and seeing mostly sick people and thinking that can be generalized to society.

Why would you ask old people if young people are healthier than they were? Surely, Spain compiles medical statistics.

Anyway, Spain appears to have the same weight issues as everywhere else:

https://pmc.ncbi.nlm.nih.gov/articles/PMC9105543/