well... crackers, cheese, salamis, trail-mix, jerky... don't have much water in them. In other words they have a fairly high calorie density. Lighter stuff will not have as many calories. If you want to up the calorie density, you have to up the fat content. More cheese, salami, peanut butter, chocolate. Of course your body has to be able to function with that kind of diet (something you might want to verify before hand).