I'm consistently an undereater on the bike. I might have part of an energy bar, a banana, a couple of Clif blocs or a few cookies every 20-25 miles but I otherwise don't each much. For rides under 2 hours, I usually don't have anything at all. For longer rides (century or more), I'll try to nibble a bit more and eat a more substantial lunch, but I don't think I come close to replacing my calorie expenditure. My appetite off the bike, however, is voracious. I call it "feeding the beast." If my blood sugar takes a dive, I barely recognize myself, I get so cranky. I keep something in my purse at all times just in case--under orders from my boyfriend. 
I did find that my post-ride appetite is easier to control when I consistently drink chocolate milk immediately after a ride. I tend to agree that the carb/protein combination helps keep hunger in check and aids in recovery.
One thing I've consistently read is that cyclists sometimes overdo it with energy drinks--on and off the bike. So, if you're having trouble losing or maintaining weight, you might take a close look at how much you're drinking and whether water is sufficient for your shorter/easier rides.
Live with intention. Walk to the edge. Listen hard. Practice wellness. Play with abandon. Laugh. Choose with no regret. Continue to learn. Appreciate your friends. Do what you love. Live as if this is all there is.
--Mary Anne Radmacher