There are many factors that affect our daily calorie requirements :-
1) Physical activities
Different physical activities use different amount of energy, The
more active we are the more energy we need.
2) Body size
When the number of cells in the body increase, the size of the
body gets bigger. As every cells requires energy to function
properly and stay alive, a person with a larger body size will have a higher calorie requirement.
Children and teenagers need more energy than adults because they
undergo rapid growth and high metabolic rate. Adults stop growing
and their metabolic rates drop when they become older.
The energy requirement in male is generally higher than that of female of the same age and state of health.
5) State of health
Sick people need more energy to fight against diseases and repair their damaged tissues. However this does not imply that the sick need to take in food with a high calorific value. Different type of programmes for treating diseases recommend eating different types of food in varying amounts.
6) Climate or Temperature of the surroundings
Our body loses more heat in cold surroundings , As a result our calorie requirement increases because additional energy is needed to replace the heat lot to the cooler surroundings.