I lose about 10 pounds on most of my longer trips. That leaves me a little too lean. I take a lot of food and never feel undernourished. After a number of long days my bodies metabolism speeds up. When it gets really fired up I have to set in the water before bed so I can cool down and get to sleep. The same thing happens at home after an all day bike ride. The experts say that exercising hard for over an hour causes your body to burn more calories for hours after you quit the exercise.