People racing the Tour Divide, a 2700 mile solo unsupported bikepacking race through the Rocky Mountains, lose weight when riding their bikes 18 hours a day for 2-3+ weeks straight. They describe being unable to choke down enough food even though what they are eating is very calorie dense. Hotdogs, burritos, burgers, pizza, a pound of gummies every day, chocolate milk and ice cream when resupplying, McDonalds where they fill their hydration bladders with PowerAde, anything they can get their hands on quickly when they arrive at a small mountain town which frequently has nothing more than a gas station.
https://www.facebook.com/groups/tourdivide/posts/24754803527...
Obviously not a practical solution as you say but they do exercise enough to offset the food when eating as much as they can.