Diet vs. exercise
Diet is calories entering your body, providing essential fuel for everything going on beneath your skin 24/7. During exercise, these calories are burned. When calories in (diet) versus calories out (exercise) are balanced, your weight is controlled. This statement is perhaps too simplistic, since not all calories are created equal and there are other factors of caloric storage and expenditure. However, the underlying concept holds true. Eat too much and your body will store excess calories as fat. Exercise too little and your body has no need to burn this excess stored fat. In other words, if you're serious about weight loss and overall health in general, include both diet and exercise in your plan.