When I get to spend 3 hours in the saddle most days of the week I tend to loose weight what ever I do. I'm not hungry until about an hour after I go off the bike, but I'm thirsty and I can eat a banana or someting light. When I start on the fourth hour I tend to be tired, if I eat something then it helps. When I spend all day on the bike it's usually for the enjoyment as much as anything else, not pushing speed or time limits.