For anyone trying to lose weight, this question is bound to raise a lot of excitement. Surely losing weight cannot be such a simple issue, can it? Well, the answer is YES! First of all, we need to distinguish between calories and Calories. Calories (i.e. with a big c) are used to denote the amount of energy that is contained in food. Whereas calorie with a small c is used to denote the energy required to raise the temperature of 1 gram of water 1 degree Celsius.