I also often take quick 45 to 60 minute hikes with a girlfriend of mine. The good news is that even these short hikes can burn a lot of calories, as you can read here: http://blog.nutritiondata.com/dieting_weight_loss_blog/2009/08/burn-more-calories-hiking-vs-walking.html
"Typically, walking at a 20-minute mile pace will burn about 262 calories in an hour, but the good news is that hiking in just that same amount of time almost doubles your caloric expenditure at 477 calories (based on a 175 pound person)."
I weigh a lot less than 175 pounds, but I'm guessing my caloric burn during hiking is still twice as much as just plain walking. Plus, I get to enjoy the fresh air and nature.