Calories In vs. Calories Out

Calories in vs. Calories out seems simple enough right? Burn more calories than you take in and you lose weight. Now, how many of you have tried this for any length of time and found that it just does not work for you? Or, it worked for a few weeks to months and you not only put that weight back on, but can't seem to get it to happen again?

Turns out its a little more complicated than that.