Calorie is energy. It’s the unit of measurement for the amount of energy-giving content of a food or drink. The more rigorous your activities on a daily basis, the more energy you need to keep you up and running.
Before you fall into depression, take note that there are underlying factors for the phenomena. First, metabolism. If your metabolism is fluctuating due to age or body chemistry, you might need to resort to another option.
Aging also slows it down. Your activity level could also be to blame. The food you eat could also be a factor.