Well, like anything, it's a challenge to see if I can do it. It also follows my normal workout cycle (12 weeks heavy lifting, 8 weeks cardio). This is an experiment to see if I can minimise my strength loss during the cardio phase.

As for packing on calories, the foods with the highest caloric density are fats. Eat more fat. Potatoes don't have that many calories by themselves. Instead, add good mono-unsaturated fats to your diet. Fats like olive oil, or peanut oil are good, but stay away from saturated fats, as it'll adversely affect your cholesterol levels too much. Every tablespoon of oil is about 120 calories. Avocados are also a good source of fat.