Business trips are always a gain because of the big dinners and copious amounts of booze.

Leisure trips are usually a loss because we're pretty active - running and hiking being common on a lot of our trips. (We've done a lot of trips that include a marathon at the destination.) Or, even just touring a city, we tend to cover a lot of ground, usually with a mix of walking and the local subways/trains. We also tend to eat lighter meals overall and drink in moderation.