I'm sort of the same riding routine you are - commuting 12 miles each weekday and long weekend rides (if the #*%@! winter will ever end). I only worry about bonking on those long weekend rides and it seems to work to eat small amounts of high energy type food spaced out during the ride along with some sort of electrolyte replacement drink, then eating SOON after finishing the ride, but just a regular lunch or dinner, not vast quantities. I was bonking when I waited until the end of the ride and then having all sorts of recovery issues if I didn't eat within that 30-45 minute window after I rode. The extra calories from the ride snacking never had any impact on the weight loss. So much depends on the thriftiness of our metabolism, though!