3 facts and 1 clarification:
 
The Facts:
  1. One can lose weight by eating less.
  2. One can lose weight by exercising more.
  3. One can lose even more weight by both eating less and exercising more.


The Clarification:

The body needs a minimum number of calories for proper body function. If fact # 1 is taken to an extreme such as hardly eating anything or even skipping meals outright, then the body will shut down the process that burns calories, as it goes into survival mode and starts hoarding calories into body fat.

If you are in the middle of a weight loss routine, be sure to modestly address your hunger (to the point that the hunger signs go away but not to a extreme of overindulgence).