You also have to be realistic about how much "energy" you really need. We all love to think we are these world class athletes, but my backpacking seldom seems difficult. The more you are in shape, the less effort you use, so less calories needed. PCT hikers are different- they do 20+ miles a day, day after day. I do not fool myself into thinking that I am doing anything near that. I have been out for up to 100 days straight and do eat more after 2 weeks. We used to say that we finally got our "mountain appatite". The best method is to keep track of the food you do not use on a trip. Careful evaluation of this will help you do better meal planning on future trips. For example: No matter how much cheese I take, I always eat it! I burn out on trail bars (too sweet). As much as I love almonds, last trip I burned out on them and had half a bag left when I got home. No matter how much dried/fd fruit I bring, I eat it all. I usually bring too many hot drinks. As much as I like hot drinks, I usually do not have enough fuel to heat enough water. You really need to match your food that requires hot water with the amount of fuel you bring. So now I take dark chocolate squares to get my chocolate fix after dinner instead of hot cocoa.