It likely does not make much a difference. Geoff does his runs in the mountains during the late Spring through late Fall. We're talking about thousands of feet of elevation change each day. It appears that Geoff also only runs once a day. An occasional frozen pizza before bed won't make much a difference given his mileage and work ethic. Geoff also has access to an abundant supply of quality fruits and vegetables at Rainbow Foods.
"Roes says it can be a lot of work to avoid a caloric deficit, which makes sense when your daily run ranges from three to seven hours long."
- Juneau Empire article