It's been a very steady pattern with me. Each time I've left a desk job to go cruising I've lost weight.
Happened in 1995 on our first boat, 2009 when we left Vancouver on the current boat, and again this past few months when we left Brisbane in early July. Now I had been diligently riding my bike, and really watching what I ate in Brisbane, and the kilos were being shed.
What happens when I don't really watch what I eat, but re-start an active lifestyle? Pulling on halyards, grinding in sheets, lifting the dinghy in the davits almost every day. Walking everywhere, swimming, doing boat chores. It all adds up. Yay me.
So if you want to lose weight, consider a sailing lifestyle.*
* this may not apply to female sailors for some reason (seriously). Many of them report weight gain when they go cruising.