Massive, the local lake has a big community over winter , quite a few older people also that love the social aspect and (generalisation here) some may have no other social interaction of a day. even younger people that “WFH” a lot. I mainly come to the office to see people and go for a swim at the hospital, not for any desire to be “in the office”
Brining it back on topic, psychological reasons for obesity are not in doubt either. People do eat when lonely, eat when sad etc and a quick dip and a slice of cake whilst out in the fresh air for 2 or 3 hours is probably better than sitting down watching TV and eating alone which they may do instead
