A lot of brain time can be spent on planning on foraging for food in an emergency. In many areas there is no food to be foraged upon when you need it. MANY calories are spent on foraging. So don't forage. Plan instead.

Assuming you have water and shelter, 1500 calories per day will more than sustain you for 6 months. You will be lean and mean but you will be sustained. 1500 calories per day for 30 days and you will have just lost a bit of weight.

List where you spend your time that you think you may get stranded. People are creatures of habit. It won't be as many areas as you may think.

Now, can you always be somewhat near a 5 gallon plastic bucket with a little planning? Half of the large survival food bars is equal to 1800 calories. One pound of Purina Puppy Chow is equal to 1730 calories.

A good read is the "MINNESOTA STARVATION EXPERIMENT".