Many clients have misconceptions about the amount of calories they expend. They are usually surprised and discouraged to learn a typical exercise session, for a person of average fitness, burns only about 300 calories. Weight loss is simple, really. You need to burn more calories than you eat.
Calorie expenditure has 3 components:
- Resting metabolic rate
- Energy expended with exercise
- The type of food you are consuming
Heavier people expend more calories with exertion than lighter people because they have to work harder to move and exercise... Fit people have to work longer, harder and work out more often to expend a lot of calories.
That is why the formula is diet AND exercise. Not just one or the other.